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Getting useful readings out of GSR sensors while moving?

Getting useful readings out of GSR sensors while moving?



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I'm currently thinking about a project that would involve using a GSR sensor and an Arduino (Probably the Grove GSR Sensor) to measure Stress levels in a person.

It will not be a research project, but an art project instead. I want to build a device that shows my stress level with some LEDs as indicators. The idea is that I can walk around with it and when I approach people and talk to them the color changes because of my social anxieties. So it doesn't have to be accurate, but if it won't work at all, I might as well scrap the project.

In which ways would movement of the subject distort the readings? Suppose the wearer has heightened physical activity, would the GSR sensor give any useful readings? And if so: any pointers on how to pull this off?


I think the general downside of the galvanic skin response (GSR) apply here. Wikipedia sums up a few confounding factors that affect the validity of GSR:

  • Temperature and humidity (affect the resistance of the skin and hence GSR);
  • Internal factors, such as medications and hydration;
  • Different locations of measurement on the body can lead to different responses; for example, the responses on the left and right wrists are driven by different regions of the brain, providing multiple sources of arousal.
  • Different body parts may have different sweat gland density
  • Electrodermal responses are delayed 1-3 seconds.

My personal biggest issue with the method is the fact that the GSR depends so much on the temperature of the room and activity of the subject. However, my purpose for it is a quantitative one; your is more of a qualitative one as I understand it. If yes, then some variability may not be so problematic and you can counter the above drawbacks by

  • Only do the experiment indoors in a climate controlled environment;
  • Calibrate the equipment on yourself and only use yourself as a subject and stay hydrated;
  • Always use the same location (fingers in case of your linked device);
  • Give your device some time to respond; so the (stress) situation has to be somewhat prolonged, and the response will be delayed.

Do note that skin conductances are finicky. You can assure good contact by rubbing the skin with alcohol and a rough-surface pice of gauze. Make sure to apply some conductive paste. Measure the impedances regularly.

FYI: I have chosen to use pupillometry as a measure of stress. It has its own drawbacks and issues (especially adaptational responses and baseline issues), but once it works, it's less prone to signal drift, e.g. because of impedance issues as with electrode-based methods.

Below I've added a reference that lists an entire protocol for such measurements.

Reference
- Cartocci et al., J Vis Exp (2017); 126: 55872


Heart rate variability: A new way to track well-being

Information is knowledge, and big tech companies know how important it is to collect and track data. When it comes to your health, it is now easy to measure and track all kinds of information. In the comfort of our homes we can check our weight, blood pressure, number of steps, calories, heart rate, and blood sugar. Recently some researchers have started to use an interesting marker for resilience and behavioral flexibility. It is called heart rate variability (HRV).

Have you ever wondered what the health impact of a stressful day was? Will you perform well during your long run tomorrow morning? Is there anything you can do today that would improve your ability to have a better day moving forward? HRV may be the piece of data that could help you answer these questions.

What is HRV?

HRV is simply a measure of the variation in time between each heartbeat. This variation is controlled by a primitive part of the nervous system called the autonomic nervous system (ANS). It works regardless of our desire and regulates, among other things, our heart rate, blood pressure, breathing, and digestion. The ANS is subdivided into two large components, the sympathetic and the parasympathetic nervous system, also known as the fight-or-flight mechanism and the relaxation response.

The brain is constantly processing information in a region called the hypothalamus. The hypothalamus, through the ANS, sends signals to the rest of the body either to stimulate or to relax different functions. It responds not only to a poor night of sleep, or that sour interaction with your boss, but also to the exciting news that you got engaged, or to that delicious healthy meal you had for lunch. Our body handles all kinds of stimuli and life goes on. However, if we have persistent instigators such as stress, poor sleep, unhealthy diet, dysfunctional relationships, isolation or solitude, and lack of exercise, this balance may be disrupted, and your fight-or-flight response can shift into overdrive.

Why check heart rate variability?

HRV is an interesting and noninvasive way to identify these ANS imbalances. If a person&rsquos system is in more of a fight-or-flight mode, the variation between subsequent heartbeats is low. If one is in a more relaxed state, the variation between beats is high. In other words, the healthier the ANS the faster you are able to switch gears, showing more resilience and flexibility. Over the past few decades, research has shown a relationship between low HRV and worsening depression or anxiety. A low HRV is even associated with an increased risk of death and cardiovascular disease.

People who have a high HRV may have greater cardiovascular fitness and be more resilient to stress. HRV may also provide personal feedback about your lifestyle and help motivate those who are considering taking steps toward a healthier life. It is fascinating to see how HRV changes as you incorporate more mindfulness, meditation, sleep, and especially physical activity into your life. For those who love data and numbers, this can be a nice way to track how your nervous system is reacting not only to the environment, but also to your emotions, thoughts, and feelings.

How do you check your heart rate variability?

The gold standard is to analyze a long strip of an electrocardiogram, the test we frequently do in the medical office where we attach wires to the chest. But over the past few years, several companies have launched apps and heart rate monitors that do something similar. The accuracy of these methods is still under scrutiny, but I feel the technology is improving substantially. A word of caution is that there are no agencies regulating these devices, and they may not be as accurate as they claim. The easiest and cheapest way to check HRV is to buy a chest strap heart monitor (Polar, Wahoo) and download a free app (Elite HRV is a good one) to analyze the data. The chest strap monitor tends to be more accurate than wrist or finger devices. Check your HRV in the mornings after you wake up, a few times a week, and track for changes as you incorporate healthier interventions.

The bottom line

Tracking HRV may be a great tool to motivate behavioral change for some. HRV measurements can help create more awareness of how you live and think, and how your behavior affects your nervous system and bodily functions. While it obviously can&rsquot help you avoid stress, it could help you understand how to respond to stress in a healthier way. There are questions about measurement accuracy and reliability. However, I am hoping an independent agency eventually identifies which devices and software provide data we can trust. In the meantime, if you decide to use HRV as another piece of data, do not get too confident if you have a high HRV, or too scared if your HRV is low. Think of HRV as a preventive tool, a visual insight into the most primitive part of your brain.


2-6 Months: Getting to Know Who Mom Is

The child starts to get a sense of how his or her mother will react when they are anxious or distressed.

The infant's early expectation of his or her mother's responsiveness lays the ground for the specific attachment behavior the infant will develop in half a year's time.

Attachment behavior of this stage is characterized by:

  • Reaching out for, grasping hold of and clinging to the mother (of course crying, smiling and continuous vocalizing still occurs).

Mind-reading device uses AI to turn brainwaves into audible speech

Electrodes on the brain have been used to translate brainwaves into words spoken by a computer – which could be useful in the future to help people who have lost the ability to speak.

When you speak, your brain sends signals from the motor cortex to the muscles in your jaw, lips and larynx to coordinate their movement and produce a sound.

“The brain translates the thoughts of what you want to say into movements of the vocal tract, and that’s what we’re trying to decode,” says Edward Chang at the University of California San Francisco (UCSF). He and his colleagues created a two-step process to decode those thoughts using an array of electrodes surgically placed onto the part of the brain that controls movement, and a computer simulation of a vocal tract to reproduce the sounds of speech.

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Read more: Mind-reading headset lets you Google just with your thoughts

In their study, they worked with five participants who had electrodes on the surface of their motor cortex as a part of their treatment for epilepsy. These people were asked to read 101 sentences aloud – which contained words and phrases that covered all the sounds in English – while the team recorded the signals sent from the motor cortex during speech.

There are about 100 muscles used to produce speech, and they are controlled by a combination of neurons firing at once, so it’s not as simple as mapping signals from one electrode to one muscle to sort out what the brain is telling the mouth to do. So, the team trained an algorithm to reproduce the sound of a spoken word from the collection of signals sent to the lips, jaw and tongue.

Electrodes like this were used to record brain activity

The team says “robust performance” was possible when training the device on just 25 minutes of speech, but the decoder improved with more data. For this study, they trained the decoder on each participant’s spoken language to produce audio from their brain signals.

Once they had generated audio files based on the signals, the team asked hundreds of native English speakers to listen to the output sentences and identify the words from a set of 10, 25 or 50 choices.

The listeners transcribed 43 per cent of the trials perfectly when they had 25 words to choose from, and 21 per cent perfectly when they had 50 choices. One listener provided a perfect transcription for 82 sentences with the smaller word list and 60 with the larger.

“Many of the mistaken words were similar in meaning to the sound of the original word – rodent for rabbit – therefore we found in many cases the gist of the sentence was able to be understood,” says team-member Josh Chartier at UCSF. He says the artificial neural network did well at decoding fricatives – sounds like the ‘sh’ in ‘ship’ – but had a harder time with plosives, such as the ‘b’ sound in ‘bob’.

“It’s intelligible enough if you have some choice, but if you don’t have those choices, it might not be,” says Marc Slutzky at Northwestern University in Illinois. “To be fair, for an ultimate clinical application in a paralysed patient, if they can’t say anything, even having a vocabulary of a few hundred words could be a huge advance.”

That may be possible in the future, he says, as the team showed that an algorithm trained on one person’s speech output could be used to decode words from another participant.

The team also asked one person to mimic speech by moving their mouth without making any sounds. The system did not work as well as it did with spoken words, but they were still able to decode some intelligible speech from the mimed words.

Similar devices have been created that attempt to decode brain signals directly into sound, skipping the simulation of motion around the mouth and vocal tract, but it’s still unclear which approach is most effective.

This device doesn’t rely on signals for creating sound, but just on those for control motor functions, which are still sent even if someone is paralysed. So, this device could be useful for people who once were able to speak but lost that ability due to surgery or motor disorders like ALS, in which people lose control of their muscles.


The emotion sensing wearables that sadly didn't make it

Making wearables is hard, but it's clear that making ones that can tell us how we feel can be even harder. We've covered devices that made big promises of tapping into our emotions, but ultimately failed at the first hurdle.

Like Upmood (pictured above), which claimed to collect a host of biometric data including heart rate to to deliver live emotion detection along with stress readings. It failed to raise the necessary funds on Kickstarter to make it a reality.

UK startup Vinaya was planning to launch its Zenta biometric bracelet, which raised over $200,000 on Indiegogo and was scheduled to ship in January 2017. The piece of smart jewellery, which works just like a fitness tracker, also tracked emotions to improve overall wellbeing. Vinaya unfortunately fell into administration, and with it the chances of ever seeing its innovative tech.


The 7 Best Sleep Trackers of 2021, According to Experts

Elizabeth Yuko, PhD, is a bioethicist and journalist, as well as an adjunct professor of ethics at Fordham University. She has been published in The New York Times, The Washington Post, Rolling Stone, The Atlantic, CNN, Teen Vogue, and more.

Ashley Hall is a writer and fact checker who has been published in multiple medical journals in the field of surgery.

Our editors independently research, test, and recommend the best products you can learn more about our review process here . We may receive commissions on purchases made from our chosen links.

Our Top Picks

"Simply place the pad under the mattress, and find out data like your sleep cycles, breathing disturbances, and heart rate."

"In addition to its wide range of wellness functions, it offers personalized insights and tips to improve your sleep quality."

"Ideal if you appreciate a more compact accessory than a watch, this smart ring uses an infrared LED sensor to track your sleep."

"Especially helpful for those with respiratory conditions, it measures blood oxygen levels, sleep debt, and sleep quality."

"Compatible with any kind of mattress, it connects to an app to provide users with an AI sleep coach that offers feedback."

"If you appreciate versatility, the smartwatch tracks both daytime naps and daily sleep while also offering over 70 sports modes."

"Complete with Alexa to help you round out your smart home, it uses an app to offer personalized tips on improving sleep."

If you’re someone who reliably gets restful nights of sleep, then you may not fully realize how detrimental insomnia or disrupted sleep can be for your physical and mental health. And it’s not just a lack of sleep: poor sleep hygiene—including not sticking to a sleep schedule—can also make us feel worse.

There are also situations where a person might think they’re sleeping well, but, following observation, find out that their sleep is disturbed regularly by everything from nightmares, temperature fluctuations, or conditions like sleep apnea. Whatever the cause, it can be helpful to be able to track your sleep to see what you get up to at night and what adjustments you can make to improve your overall sleep quality and potentially even your mental health.

Fortunately, you no longer have to spend the night in a sleep lab to get data like that because there are a variety of sleep trackers available, either as wearables or other forms of technology. But if you’re new to these products, it can be difficult to know which one to choose.

To help make that task easier, we spoke with the experts to find the best sleep trackers on the market.


How are balance disorders treated?

The first thing an otolaryngologist will do if you have a balance problem is determine if another health condition or a medication is to blame. If so, your doctor will treat the condition, suggest a different medication, or refer you to a specialist if the condition is outside his or her expertise.

If you have BPPV, your otolaryngologist or audiologist might perform a series of simple movements, such as the Epley maneuver, to help dislodge the otoconia from the semicircular canal. In many cases, one session works other people need the procedure several times to relieve their dizziness.

If you are diagnosed with Ménière's disease, your otolaryngologist may recommend that you make some changes to your diet and, if you are a smoker, that you stop smoking. Anti-vertigo or anti-nausea medications may relieve your symptoms, but they can also make you drowsy. Other medications, such as gentamicin (an antibiotic) or corticosteroids may be used. Although gentamicin may reduce dizziness better than corticosteroids, it occasionally causes permanent hearing loss. In some severe cases of Ménière's disease, surgery on the vestibular organs may be needed.

Some people with a balance disorder may not be able to fully relieve their dizziness and will need to find ways to cope with it. A vestibular rehabilitation therapist can help you develop an individualized treatment plan.

Talk to your doctor about whether it's safe to drive, and about ways to lower your risk of falling and getting hurt during daily activities, such as when you walk up or down stairs, use the bathroom, or exercise. To reduce your risk of injury from dizziness, avoid walking in the dark. Wear low-heeled shoes or walking shoes outdoors. If necessary, use a cane or walker and modify conditions at your home and workplace, such as adding handrails.


To tell the truth

Perhaps the most well-known use of galvanic skin response is the lie detector test, formally known as the polygraph machine. Along with measuring heart rate, respiration rate, and blood pressure, the polygraph measures galvanic skin response as questions are asked. A polygrapher is trained and qualified to interpret the responses to the questions, but standardized questioning procedures must be followed to get an accurate reading.

Initially, the polygrapher asks questions that are obviously true or false, such as “Is your hair blonde?” to establish a baseline reading. Questions with answers unknown to the polygrapher are then asked and the readings are compared to the baseline to determine whether the subject is telling the truth.

Other uses of galvanic skin response allow us to discover how the body is really responding without our conscious filters getting in the way. Galvanic skin response is such a valuable way to observe how the body reacts to certain stimuli that it’s been utilized in a wide variety of fields for several decades. Some of the areas in which GSR technology is used include:

  • Psychological research
  • Psychotherapy
  • Media and ad testing
  • Usability testing
  • Consumer neuroscience
  • Health care

The emotion sensing wearables that sadly didn't make it

Making wearables is hard, but it's clear that making ones that can tell us how we feel can be even harder. We've covered devices that made big promises of tapping into our emotions, but ultimately failed at the first hurdle.

Like Upmood (pictured above), which claimed to collect a host of biometric data including heart rate to to deliver live emotion detection along with stress readings. It failed to raise the necessary funds on Kickstarter to make it a reality.

UK startup Vinaya was planning to launch its Zenta biometric bracelet, which raised over $200,000 on Indiegogo and was scheduled to ship in January 2017. The piece of smart jewellery, which works just like a fitness tracker, also tracked emotions to improve overall wellbeing. Vinaya unfortunately fell into administration, and with it the chances of ever seeing its innovative tech.


Frequently Asked Questions

Don’t see your question below? Check out our knowledge-base here, and simply type in your question into the smart-search bar.

You can also send us questions and comments from within the app, the Team Dashboard, or on the contact form here.

Q: How much does the Elite HRV app cost?

The Elite HRV app is free for iOS and Android! You can get the app here for iOS or Android.

Q: Where can I view HRV trends and other data?

All data is collected from the Elite HRV app on Android or iOS. It is then securely synced to the user’s private account in the cloud. If the user is connected to a Team, then the data automatically syncs to the Team Web Dashboard as well.

Certain trends (such as Daily Readiness, Heart Rate Variability and Heart Rate) are viewable directly from your preferred phone or tablet. More advanced trends (such as Coefficient of Variation, Sleep, Exercise) can be found on the web dashboard (link). The web dashboard is currently geared towards organizations and teams, but there is nothing stopping an individual from creating a personal team to make use of the web dashboard. A personal version of the web analysis dashboard is in the works.

Currently data can be exported from both the app and the web dashboard. Data exported from the app comes in raw R-R interval form and is sent to the email address associated with your app account. Data exported from the web dashboard is in the processed and calculated form and can be saved directly to your computer.

Q: What devices are compatible with the Elite HRV app?

(See this dedicated page for a full breakdown of compatible devices)

Compatible Phones, Tablets, and Smart Devices

The Elite HRV app can be found on both Google Play and the App Store. It is compatible with the following devices:

  • Most Android devices that run Android 4.3 or newer are compatible
  • Learn: How to update your Android OS to the latest version
  • Must have Bluetooth 4.0 (also called Smart or LE)
  • Nexus 4, 5, 7 (2nd edition), 10
  • Samsung Galaxy Series

Compatible Heart Rate Monitors

To accurately measure Heart Rate Variability and transmit it to your compatible phone or tablet the heart rate monitor must have: 1.) Bluetooth 4.0 (also called Smart or LE), 2.) Accurate R-R Interval Recording (also called inter-beat intervals). Here is a list of Elite HRV-compatible heart rate monitors:

(See this dedicated page for a full breakdown of compatible devices)

Q: Why can’t I use my wrist HR monitor or LED/pulse oximetry monitors like Fitbit?

Unfortunately, at this time the available wrist band monitors, watches, and finger sensors that use Pulse Oximetry or LED to detect heart rate do not accurately measure (or do not support) R-R intervals. R-R intervals are the exact time measurements between each heart beat that are needed for truly accurate HRV calculations. Due to the limitations of those hardware devices, we do not recommend them for reliable HRV readings.

These devices are fine for just getting your basic heart rate though!

These devices include the Fitbit Charge HR, Mio wrist devices, Polar wrist devices, Apple Watch, etc. We hope the hardware will advance sometime soon and provide accurate R-R intervals (We know they are very convenient!). In the meantime, the best option is to invest in a chest strap heart rate monitor. For convenience, here is a link to our current recommended chest strap: https://elitehrv.com/heartmonitor

Q: How far away from the app can I go during my workout or other activities?

The answer to this varies based on your hardware (and has almost nothing to do with the app). That being said, the Elite HRV app is designed to remain connected as long as you are within signal range (even if some heart beats are dropped due to distance). If you go completely out of connection range you may lose the connection entirely and need to restart the reading.

Our testing:

We have run tests at various distances and found the most accuracy and consistency within 15 feet. Outside of that range intermittent skipping of beats increases with distance – more details on testing below:

Recommended – Under 15 feet away – consistent signal for short-term sampling Generally Acceptable (not for extended periods of time) – 15 to 30 feet away – intermittent loss of heart beats (R-Rs) Not Recommended – 35+ feet – consistent loss of R-Rs Notes: This was tested indoors with other electronic equipment in the near vicinity. Results may vary by receiving device, heart rate device, in outdoor open areas or depending on your equipment arrangements indoors.

Q: What is Heart Rate Variability?

Basic Heart Rate Variability (HRV) is the measured changes of the time intervals between successive heart beats. Unlike Heart Rate (HR) that averages the number of heart beats per minute, HRV looks much closer at the small fluctuations of the heart that occur in response to internal and external events.

Learn more about HRV and how it ties to your Autonomic Nervous System: https://elitehrv.com/what-is-heart-rate-variability/

Q: How is Heart Rate Variability useful?

Knowledge is power. By applying the appropriate research-backed calculations to Heart Rate Variabililty (Elite HRV does that for you), you can better understand your nervous systems, cardiovascular systems, and respiratory systems in response to life’s stressors.

By incorporating your HRV insights, you have a powerful tool to help optimize training, manage stress and improve health.

Q: Will the app show me my ability to handle stress or exercise each day?

Yes, each day that you take a Morning Readiness reading, you get a Colored Indicator, Autonomic Balance Gauge, and Morning Readiness Score that give you insight into your stress and recovery patterns.

Q: Can I use Elite HRV to 'train' my heart and nervous system?

Elite HRV has built in breathing guides that allows you to use your respiratory system to gain control over your cardiovascular system and nervous system and track the effects. However, it does not automatically guide you towards a state of “coherence.”

Q: Why is it important to measure HRV (Morning Readiness) in the morning instead of other times throughout the day?

The best way to determine your individual heart rate variability and thus nervous system activity is to take a short (1-5 min.) reading each day. Ideally you want the reading to happen at the same time, in the same way, so as to eliminate as many affecting variables as possible.

Throughout the day many factors can affect HRV. Internal processes like circadian rhythm and hormonal fluctuations cause it to slowly rise and fall over 24 hours. Also whatever you were doing before taking a reading has a very strong impact on the reading. Mental, physical and emotional experiences all affect HRV.

This is why we recommend taking the reading each morning. When you have just awoken you haven’t had the chance to experience the stresses of work, school, or the day. Your circadian rhythm and hormonal patterns should be consistent at that time as they were the previous day. We also recommend that you breath naturally for the Morning Readiness and take the reading in the same body position each time.

By calculating your baseline first thing each morning, you can eliminate a lot of variables and highlight the patterns that matter most. This allows you to cut through the “noise” and get insights about how recovered you are and how ready you are to tackle the day’s challenges.

Q: How do you calculate the HRV score?

Our HRV score process is broken down as follows:

  • We capture the R-R intervals via the chest strap heart rate monitor.
  • We apply the RMSSD calculation. Root Mean Square of Successive Differences (RMSSD) is the industry standard, time domain measurement for detecting Autonomic Nervous System activity in short-term durations (5 minutes or less).
  • A natural log (ln) is applied to RMSSD. Since RMSSD behaves logarithmically, it is difficult to conceptualize the magnitude of changes as it rises and falls. Therefore, it is common practice in the application of RMSSD to apply a natural log to produce a number that behaves in a more linearly distributed fashion.
  • The ln(RMSSD) is expanded to generate a useful 0 to 100 score. The ln(RMSSD) value typically ranges from 0 to 6.5. Using over 1,000,000 readings from our database, we have been able to sift out anomalous readings and create a much more accurate scale where everyone fits in a 0 to 100 range.
Q: What is a good HRV score?

Heart rate variability is highly based on individual circumstances. Everything from your mindset to air quality to age and exercise patterns can affect HRV. This is why we emphasize the personal trends and improvement over comparing yourself to others.

That being said, where do you stack up?

  • The average HRV score is 59.3 for Elite HRV users
  • This post covers values for your age, gender and the Elite HRV population breakdown: https://elitehrv.com/normal-heart-rate-variability-age-gender/

A higher HRV is correlated with younger biological age and better aerobic fitness. We have a lot of young athletes as users, and they are setting the bar high! Remember the key to improvement is acute stress (training) followed by adequate recovery.

Scoring really low on any given day is usually nothing to worry about. It is your average over time that matters the most. Working towards improving your average HRV over time is a good and achievable goal.

Q: What are HRV score, RMSSD, ln(RMSSD), SDNN, NN50, and PNN50?

Our HRV score is calculated from the RMSSD and represents the strength of your Autonomic Nervous System at a given time. The other numbers provided are for reference for those interested in in more detailed analysis of their HRV data.

Here’s a quick run down of what they mean (NN or R-R intervals means the time between two successive heart beats):

RMSSD: Root mean square of the successive differences – used for a good snapshot of the Autonomic Nervous System and is the basis of our “HRV Score”

  • RMSSD is strongly backed by research and is considered the most relevant and accurate measure of Autonomic Nervous System activity over the short-term. Here are a few studies referencing its use:

ln(RMSSD): A natural log is applied to the RMSSD in order to distribute the numbers in an easier to understand range

SDNN: Standard deviation of the NN (R-R) intervals

NN50: The number of pairs of successive NN (R-R) intervals that differ by more than 50 ms

PNN50: The proportion of NN50 divided by the total number of NN (R-R) intervals

Q: What do the Green, Yellow, and Red indicators mean on the Morning Readiness reading analysis?

Grey: You see this indicator type on your first Morning Readiness reading (or if you haven’t taken a MR reading in a while). The grey indicator with a score of n/a shows that you need to establish a baseline of a few days to compare to before you can start receiving Morning Readiness scores, indicators, and recommendations.

Green: indicates that compared to your own personal trends, you should be able to handle more stress today. This often includes being able to:

  • Exercise a little harder than normal
  • Tackle a few more items on your to-do list
  • Think a little more clearly at work or school
  • Have reduced systemic inflammation

Yellow (Sympathetic): indicates the body is under a bit more stress than usual. Consider lighter exercise and reducing stressful activity unless you have restful days coming up or if over doing it is not a concern.

Yellow (Parasympathetic): indicates the body’s recovery systems are working overtime to recover from a large or accumulated stress. This state is correlated with over reaching in training or over-active parasympathetic (recovery) systems.

Red (sympathetic): indicates the body is experiencing deeper levels of stress or fatigue. To avoid over training or over stressing it is highly recommended to prioritize rest.

Red (parasympathetic): indicates a deeper level of recovery activity in response to accumulated stress. The body is likely reaching an over trained state. It is strongly recommended to prioritize light active recovery.

Q: How does my HRV score determine Readiness?

As you take readings over time, the app establishes an individual baseline for you. The baseline is determined by the average HRV over the past 10 days of Morning Readiness readings.

When you take a new Morning Readiness reading, the app compares it to your baseline to determine if you are experiencing more stress, more recovery or are fairly similar to your baseline. (Important emphasis: The determination is relative to your own individual baseline!)

The app adjusts the sensitivity of the readiness gauge based on your baseline trends as well. If you are quite stable (i.e. only change a few HRV points from day to day), then a small change in HRV can register as a large change in readiness. Conversely, if you are fairly variable (large HRV score differences from day to day), then another moderately large swing in HRV score may possibly not affect readiness if it is within your normal bounds.

Q: Do you want to always get a Green indicator?

Green indicators are definitely good, but you may not want to get them all the time. Here are a few scenarios to consider:

If you are constantly stressed out mentally, emotionally or physically (over training) then you want to strive for Green as often as possible.

If your stress levels are under control and improving athletic training, exercise or movement is your goal, then you want to at least dip into the yellow 1-2 times a week to ensure you are stimulating your body adequately. If you are training for sports or more advanced movement/exercise then you may want to push it more often.

Remember: Stress causes adaptation. The right amount and type of stress (paired with adequate recovery) produces improvement and the wrong amount and type of stress can cause breakdown.

Q: Is a higher HRV always 'better'?

A higher HRV is generally a good thing, but there are exceptions which the app picks up on. You want your HRV to gradually increase over time (weeks, months, years). If you have taken a few Morning Readiness readings, you know that your HRV can go up and down slightly from day to day. This is normal and generally healthy.

Most folks understand that if your HRV drops a significant amount, it is indicating that you are likely experiencing abnormal amounts of stress (Sympathetic NS activity). It is then recommended to prioritize rest and recovery for optimal long-term results. However, it is less intuitive that the same can be said if your HRV rises a significant amount in a short period of time. If your HRV rises abnormally high (above a certain standard deviation) within a day or a few days, the app indicates with a yellow or red that you are likely experiencing abnormal amounts of recovery (Parasympathetic NS activity). This is often in response to accumulated amounts of stress.

Here are a few scenarios resulting in a high HRV score paired with a yellow or red readiness indicator:

  • Over training – Over reaching and over training can occur when you repeatedly experience a level of stress that your body can’t recover from. This often registers as decreasing HRV over the course of a few days, followed by a sharp increase in HRV suddenly one day. This happens because at a certain point, your body reaches a threshold where it has to stop prioritizing the fight or flight stress response, and goes into a deep recovery.
  • Mild sickness
  • Change in exercise routine
  • Change in sleep patterns

It is important for your body to go into deep recovery mode if it needs it. If you interrupt this process, you pose the risk of over training and/or not recovering fully from whatever stress your body is recovering from. This can have negative impacts on training improvements and longer term health.

One way Elite HRV tries to help you better understand your HRV scores in relation to your Autonomic Nervous System status is through our Autonomic Balance Gauge, Readiness Color Indicator, and Readiness Score. These additional readiness indicators increase clarity of what the HRV score means.

Q: How are HRV and blood pressure related?

Baroreceptors, which are the body’s natural blood pressure sensors located in the aortic arch and internal carotid arteries, contribute to heart rate variability. When you inhale, heart rate increases. Blood pressure rises about 5 seconds later. Baroreceptors detect this rise in blood pressure, which leads the system to automatically relax the blood vessel and fire more rapidly. When you exhale, heart rate decreases. Blood pressure falls about 5 seconds later. (Gevirtz & Lehrer, 2003 Lehrer & Vaschillo, 2008).

In our current library, we do not have any research that indicates certain HRV scores correlate with certain blood pressure levels, but we will keep an eye out for it and let you know if we find reliable research.

Q: Why are the HRV calculation results different than other HRV apps or systems?

Research standardized calculations such as RMSSD can still appear slightly different between systems. This could be due to differences in hardware (heart rate monitors, etc.). But it is usually due to differences in the way misreads and signal noise are handled. On the software side we calculate out misreads and signal noise as best as possible. Each system has their own method for calculating these misreads out (and some systems don’t even do this). This could potentially cause the same inputs and calculations to produce different final results. To minimize the possibility of misreads from your heart rate monitor please ensure the following:

  1. Thoroughly moisten the chest strap
  2. Tighten or loosen the strap to ensure it does not move across the skin during the reading
  3. Make sure the battery in the strap is not low
Q: Why do back to back readings sometimes produce different results?

As you have learned in our free guide, many factors affect Heart Rate Variability. The following answer assumes that you are taking readings back to back in a resting position (such as Morning Readiness readings).

The most relevant factors for differing back to back readings include structural stressors, breathing patterns and mental/emotional state. Let’s break this down.

Structural Stressors

Depending on the position you take your reading in, your body goes through phases of structural comfort and discomfort (sometimes cyclically as you make small subconscious shifts) in holding that same position. Think of this in terms of doing an isometric exercise such as holding a plank. The first 10 seconds may seem easy, but the last 10 seconds are quite stressful, and occasionally throughout you may shift your weight for some temporary relief. If you’ve ever looked at heart rate from the beginning of a plank to the end, you will see quite a difference in most cases.

Knowing this, the longer you stay in a position the more structurally stressful it can be and it can cause changes in subsequent back to back HRV readings. In other words, if you sit for 2.5 minutes it is much different than sitting for 7-8 minutes (the span of 3 Morning Readiness readings). This particular variable is less relevant in a comfortable lying position, in which case the opposite may occur – one may get more comfortable as the position is maintained.

Mental and Emotional State

Why does heart rate elevate when one gets on stage for a public speaking engagement? Our mental and emotional states can have a profound impact on our physiology at any given moment.

Regarding to back-to-back readings: Your expectations of different results, potential boredom, annoyance or excitement can all affect the outcome in addition to the other variables. In our experience, these particular changes (like boredom and annoyance) start occurring a little after the initial 2 minute mark in most people.

This is one of the reasons for the 2.5 minute Morning Readiness length as well as why subsequent readings in the same position can get increasingly affected by mental and emotional state.

Breathing Patterns

Breathing patterns have a large effect on HRV. You might have guessed at this point that breathing patterns change over time.

Breathing patterns are regulated by your body’s needs automatically unless conscious control is asserted. Two large influences on breathing patterns in a static resting position are structural stress over time and mental/emotional state.

In general the more calm, comfortable and parasympathetic you are, the longer and deeper your exhaling is. As you get more excited or uncomfortable, typically breath becomes more shallow – especially on the exhale. A great test you can perform to see these effects are to take a 1 minute reading just looking out a window and breathing freely – then immediately take another reading in the same position but following the guided breathing circle in the app at a comfortably slow pace.

So Many Factors, How Can It Be Reliable?

As you can see, in a resting position back to back readings can vary quite widely. This is the reason that we look at trends over time (days, weeks, months) and we focus on repeatable methods for measuring Morning Readiness readings.

In a series of back to back readings, the first reading is always the most relevant. It is the most comparable to the first reading on other mornings, and it eliminates as many of the factors listed above (or at least ensures that they are as comparable as possible).


2-6 Months: Getting to Know Who Mom Is

The child starts to get a sense of how his or her mother will react when they are anxious or distressed.

The infant's early expectation of his or her mother's responsiveness lays the ground for the specific attachment behavior the infant will develop in half a year's time.

Attachment behavior of this stage is characterized by:

  • Reaching out for, grasping hold of and clinging to the mother (of course crying, smiling and continuous vocalizing still occurs).

Heart rate variability: A new way to track well-being

Information is knowledge, and big tech companies know how important it is to collect and track data. When it comes to your health, it is now easy to measure and track all kinds of information. In the comfort of our homes we can check our weight, blood pressure, number of steps, calories, heart rate, and blood sugar. Recently some researchers have started to use an interesting marker for resilience and behavioral flexibility. It is called heart rate variability (HRV).

Have you ever wondered what the health impact of a stressful day was? Will you perform well during your long run tomorrow morning? Is there anything you can do today that would improve your ability to have a better day moving forward? HRV may be the piece of data that could help you answer these questions.

What is HRV?

HRV is simply a measure of the variation in time between each heartbeat. This variation is controlled by a primitive part of the nervous system called the autonomic nervous system (ANS). It works regardless of our desire and regulates, among other things, our heart rate, blood pressure, breathing, and digestion. The ANS is subdivided into two large components, the sympathetic and the parasympathetic nervous system, also known as the fight-or-flight mechanism and the relaxation response.

The brain is constantly processing information in a region called the hypothalamus. The hypothalamus, through the ANS, sends signals to the rest of the body either to stimulate or to relax different functions. It responds not only to a poor night of sleep, or that sour interaction with your boss, but also to the exciting news that you got engaged, or to that delicious healthy meal you had for lunch. Our body handles all kinds of stimuli and life goes on. However, if we have persistent instigators such as stress, poor sleep, unhealthy diet, dysfunctional relationships, isolation or solitude, and lack of exercise, this balance may be disrupted, and your fight-or-flight response can shift into overdrive.

Why check heart rate variability?

HRV is an interesting and noninvasive way to identify these ANS imbalances. If a person&rsquos system is in more of a fight-or-flight mode, the variation between subsequent heartbeats is low. If one is in a more relaxed state, the variation between beats is high. In other words, the healthier the ANS the faster you are able to switch gears, showing more resilience and flexibility. Over the past few decades, research has shown a relationship between low HRV and worsening depression or anxiety. A low HRV is even associated with an increased risk of death and cardiovascular disease.

People who have a high HRV may have greater cardiovascular fitness and be more resilient to stress. HRV may also provide personal feedback about your lifestyle and help motivate those who are considering taking steps toward a healthier life. It is fascinating to see how HRV changes as you incorporate more mindfulness, meditation, sleep, and especially physical activity into your life. For those who love data and numbers, this can be a nice way to track how your nervous system is reacting not only to the environment, but also to your emotions, thoughts, and feelings.

How do you check your heart rate variability?

The gold standard is to analyze a long strip of an electrocardiogram, the test we frequently do in the medical office where we attach wires to the chest. But over the past few years, several companies have launched apps and heart rate monitors that do something similar. The accuracy of these methods is still under scrutiny, but I feel the technology is improving substantially. A word of caution is that there are no agencies regulating these devices, and they may not be as accurate as they claim. The easiest and cheapest way to check HRV is to buy a chest strap heart monitor (Polar, Wahoo) and download a free app (Elite HRV is a good one) to analyze the data. The chest strap monitor tends to be more accurate than wrist or finger devices. Check your HRV in the mornings after you wake up, a few times a week, and track for changes as you incorporate healthier interventions.

The bottom line

Tracking HRV may be a great tool to motivate behavioral change for some. HRV measurements can help create more awareness of how you live and think, and how your behavior affects your nervous system and bodily functions. While it obviously can&rsquot help you avoid stress, it could help you understand how to respond to stress in a healthier way. There are questions about measurement accuracy and reliability. However, I am hoping an independent agency eventually identifies which devices and software provide data we can trust. In the meantime, if you decide to use HRV as another piece of data, do not get too confident if you have a high HRV, or too scared if your HRV is low. Think of HRV as a preventive tool, a visual insight into the most primitive part of your brain.


Mind-reading device uses AI to turn brainwaves into audible speech

Electrodes on the brain have been used to translate brainwaves into words spoken by a computer – which could be useful in the future to help people who have lost the ability to speak.

When you speak, your brain sends signals from the motor cortex to the muscles in your jaw, lips and larynx to coordinate their movement and produce a sound.

“The brain translates the thoughts of what you want to say into movements of the vocal tract, and that’s what we’re trying to decode,” says Edward Chang at the University of California San Francisco (UCSF). He and his colleagues created a two-step process to decode those thoughts using an array of electrodes surgically placed onto the part of the brain that controls movement, and a computer simulation of a vocal tract to reproduce the sounds of speech.

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Read more: Mind-reading headset lets you Google just with your thoughts

In their study, they worked with five participants who had electrodes on the surface of their motor cortex as a part of their treatment for epilepsy. These people were asked to read 101 sentences aloud – which contained words and phrases that covered all the sounds in English – while the team recorded the signals sent from the motor cortex during speech.

There are about 100 muscles used to produce speech, and they are controlled by a combination of neurons firing at once, so it’s not as simple as mapping signals from one electrode to one muscle to sort out what the brain is telling the mouth to do. So, the team trained an algorithm to reproduce the sound of a spoken word from the collection of signals sent to the lips, jaw and tongue.

Electrodes like this were used to record brain activity

The team says “robust performance” was possible when training the device on just 25 minutes of speech, but the decoder improved with more data. For this study, they trained the decoder on each participant’s spoken language to produce audio from their brain signals.

Once they had generated audio files based on the signals, the team asked hundreds of native English speakers to listen to the output sentences and identify the words from a set of 10, 25 or 50 choices.

The listeners transcribed 43 per cent of the trials perfectly when they had 25 words to choose from, and 21 per cent perfectly when they had 50 choices. One listener provided a perfect transcription for 82 sentences with the smaller word list and 60 with the larger.

“Many of the mistaken words were similar in meaning to the sound of the original word – rodent for rabbit – therefore we found in many cases the gist of the sentence was able to be understood,” says team-member Josh Chartier at UCSF. He says the artificial neural network did well at decoding fricatives – sounds like the ‘sh’ in ‘ship’ – but had a harder time with plosives, such as the ‘b’ sound in ‘bob’.

“It’s intelligible enough if you have some choice, but if you don’t have those choices, it might not be,” says Marc Slutzky at Northwestern University in Illinois. “To be fair, for an ultimate clinical application in a paralysed patient, if they can’t say anything, even having a vocabulary of a few hundred words could be a huge advance.”

That may be possible in the future, he says, as the team showed that an algorithm trained on one person’s speech output could be used to decode words from another participant.

The team also asked one person to mimic speech by moving their mouth without making any sounds. The system did not work as well as it did with spoken words, but they were still able to decode some intelligible speech from the mimed words.

Similar devices have been created that attempt to decode brain signals directly into sound, skipping the simulation of motion around the mouth and vocal tract, but it’s still unclear which approach is most effective.

This device doesn’t rely on signals for creating sound, but just on those for control motor functions, which are still sent even if someone is paralysed. So, this device could be useful for people who once were able to speak but lost that ability due to surgery or motor disorders like ALS, in which people lose control of their muscles.


You’re talking my language

I taught the software what my brainwaves look like by physically typing in the world “BRAIN”, then concentrating on the letters in turn. Training complete, I was then able to accurately type out “HELLO WORLD” without moving a muscle.

Your typing speed depends on the number and frequency of the flashes – a greater number takes longer, but increases accuracy – and even short words took me a minute or so to type. I can see how the system would be hugely beneficial to people with no other way of communicating, however.