Tag: sleep

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E#208 How to Interpret Sleep Data

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How to Interpret Sleep Data

Are you trying to get better quality sleep and want to know what your sleep data means? In this episode, I’m going to explain sleep hypnograms and how to use them to understand your sleep and help you sleep better.

Sleep is becoming recognised as a national health priority because it affects so many areas of life. More specifically, sleep quality and quantity are strongly linked to mental health, cognitive function, and physical injury. Sleep is regulated by multiple systems in the body including your circadian control as influenced by light and dark exposure (see previous episode).

So if you want a good night’s sleep, where do you start? Let’s consider sleep data and how you can use it to make positive changes for a better night’s sleep.

In this episode, I’ll talk about 
* What is sleep data?
* What is a sleep hypnogram?
* What does your sleep data mean?
* How can sleep data and hypnograms help improve sleep?

What is sleep data?

Sleep data includes any information collected about sleep.

It can range from information that you manually collect or write down, to data you can collect from a wearable device to data that is collected by experienced practitioners in a sleep lab.

Manual sleep data could include a sleep diary, where you write down information such as:

– the time you went to bed,

– the time you woke up,

– a subjective rating of how well you think you slept, and

– any factors that might have influenced your sleep (e.g. caffeine intake, alcohol intake, medications, use of devices, or any worries or anxiety).

The data is relatively subjective compared to other methods.

A wearable device can be used to capture physiological data while you are asleep. The data captured may include:

– the time you fell asleep,

– total duration of sleep

– sleep phases and how long you spent in each phase,

– sleep quality,

– movement during the night,

– heart rate during sleep,

– oxygen saturation during sleep,

– the time you work up.

These data may be available on a wearable itself, or in an app that syncs wearable data. Commonly, these data are combined using artificial intelligence (AI) to provide an overall sleep score that is visible on the device and/or on a related app. Examples include Whoop, Oura Ring, and Apple watch.

Other ways to capture sleep data can include nearables (non-wearable trackers that are placed near the bed which measures motion, temperature, respiratory rate, and other data), or mobile sleep apps (that detect motion in the night and/or may wake the person at the right time in their sleep cycle).

The data collected by devices like the ones mentioned may be more accurate than self-reported data but are likely to be 50 – 60% as accurate as data collected in a formal sleep lab using purpose-built equipment, according to some studies.

Many consumer wearable devices and apps use AI that is built purely from subjective data such as questionnaires, which may be biased and affect accuracy.

There is an emerging interest in wearable devices and apps such as PhiliaHealth, whose algorithms are based in actual physiological studies in a lab, and who report other unique and more actionable data. In comparison to wearables, clinical sleep studies monitor aspects such as:

– limb movement

– respiratory flow

– electrocardiograms (heart signals)

– electroencephalograms (brain activity and eye movements)

– electromyograms (muscle movements).

For most people, it is that manually-collected data or data from a wearable that is most relevant and accessible, empowering you to take action to improve your sleep.

What is a sleep hypnogram?

There are a few different ways to look at sleep data, and a sleep hypnogram is one of them.

A hypnogram is a graphical representation of your sleep cycle. It is a graph of polysomnography (PSG) data that is collected during the hours that you sleep.

The data is captured by a wearable as an activity, about every 30 seconds while you sleep. While not very precise, it allows you to capture data for different stages of sleep and graph them. These stages and the time spent in each are:

· Times you are awake and moving

· Non-REM 1 sleep (lightest sleep) (10% of sleep time)

· Non-REM 2 sleep (slightly deeper sleep) (50% of sleep time)

· Non-REM 3 sleep (also called deep sleep or slow wave sleep) (20% of sleep time)

· REM sleep (rapid eye movement, dream state, increased brain activity) (20% of sleep time

We cycle through these stages of sleep around every 90 minutes (plus or minus 20 minutes), and each person typically has 4 – 6 of these cycles each night.

Overall, 20% of sleep is spent in the REM, dreaming phase, and about 80% is spent in non-REM (also known as N-REM).

The hypnogram plot of your sleep cycle data looks something like this:

In a normal hypnogram, we might see more N-REM (Stages 1 -3) or deep sleep in the first half of the night (early sleep). Our hormonal balance is such that stimulation effects are lower at this time. 

Then, in the later part of sleep, we might notice more REM sleep in the hypnogram. During this time, the hormone acetylcholine increases to help you to process information and memories without disrupting sleep.  

People who have disruptive sleep show variations from the normal graph. They might have multiple awakenings, shorter or irregular sleep cycles, less deep sleep, and/or absent sleep stages. These changes can indicate psychiatric disorders, narcolepsy, sleep disorders, or medication effects (for example). 

Where can I find my sleep data? 

If you are using the PhiliaHealth app, your hypnogram can be found by clicking on the sleep icon on the daily dashboard, then scrolling down and click on your sleep session. 

The sleep icon shows an overall score, with total sleep time and your resting heart rate during sleep. 

Below that, the score is explained in terms of: 

  • contributing factors to good sleep (time spent in each stage and efficiency) which are colour coded in a traffic light system to show good, ok and not so good, and 
  • penalties that lower the score (restlessness, elevated heart rate and number of awakenings). 

Scroll down to see your hypnogram including the % time spent in each stage. Remember that 20% of time spent in deep sleep is ‘normal’. 

Below that, the other biometric data collected during sleep, and data on your sleep disturbances (based on arm movement). 

The traffic light colour system used in the sleep score section and the biometric data section make it easy to differentiate the positives (green) from the negatives (red). 

What does my sleep data mean? How can hypnograms help improve sleep? 

Sleep data can empower you with information that can help you make better choices to improve your sleep. According to Villanova University, sleep data can be used to: 

  • Improve knowledge and treatment of sleep conditions 
  • Identify root causes of sleep disorders 
  • Link behaviours to sleep quality 
  • Improve mattress design, and 
  • Personalise recommendations for better sleep. 

Even without going into the detail of the hypnogram and without the accuracy of laboratory-based methods, you can work out whether there are issues with your sleep and when they occur. 

  • Using your hypnogram, biometric data, sleep scores and disturbance data, you can figure out whether you’re getting enough deep sleep, and when there are potential sleep issues. 
  • You might notice that your sleep score, hypnogram and biometrics are abnormal on days that you do certain things like work late, drink alcohol, experience anxiety, use devices before bed or have noise or light nearby.  
  • Your hypnogram can show at a glance whether your sleep cycles are normal or not. 

With this information, you may be able to experiment with modifying your daytime or evening behaviours or situations to improve sleep. The data might reflect positive changes in response to behaviour change. 

By looking at trends over time and whether behaviour changes cause improvements, you can work out whether you are on track or need to get professional help from a doctor or specialist. 

Summary

This episode was a deep dive into what sleep data is, what hypnograms are, what the data means, and how you can use it to improve your sleep or identify a need to get help. 

References 

  1. Lavery, Michael & Stull, Carolyn & Kinney, Michael & Yosipovitch, Gil. (2016). Nocturnal Pruritus: The Battle for a Peaceful Night’s Sleep. International Journal of Molecular Sciences. 17. 425. 10.3390/ijms17030425.
  2. How to Use Sleep Data to Effectively Improve Rest. Master’s in Data Science.org website https://www.mastersindatascience.org/resources/sleep-data-to-improve-rest/ accessed 23/8/22.
  3. Neubauer, David N. MD. (1999) Johns Hopkins Sleep Disorders Center, Baltimore, MD in American Family Physician, 59(9):2551-2558, May 1, 1999.
  4. 4. Schellenberger Costa, Michael & Born, Jan & Claussen, Jens Christian & Martinetz, Thomas. (2016). Modeling the effect of sleep regulation on a neural mass model. Journal of Computational Neuroscience. 41. 10.1007/s10827-016-0602-z.
  5. 5. Wahaj Anwar A. Khan, Russell Conduit, Gerard A. Kennedy, Melinda L. Jackson, 2020. The relationship between shift-work, sleep, and mental health among paramedics in Australia. Sleep Health, Volume 6, Issue 3, 2020, Pages 330-337, ISSN 2352-7218, https://doi.org/10.1016/j.sleh.2019.12.002.

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E#206 Understanding Sleep Chronotypes

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Understanding sleep chronotypes

Are you intrigued by the concept of chronotypes and want to know how it can help you (or your clients) to optimise sleep, performance, health and wellbeing?

Your sleep chronotype indicates whether you’re a night owl or an early bird, and helps you optimise your sleep patterns for better focus, performance and productivity.

As someone in menopause, I want to get rid of night sweats, insomnia and brain fog as well as anxiety and low mood. For me, the research indicates that aligning with my sleep and other chronotypes will help me to reduce or eliminate these pesky symptoms.

I am trained in assessing and understanding chronotypes, so stick around to the end or check the show notes to find out how about a specific test I can help you with, to determine your chronotypes for sleep but also other areas of life like eating, exercise, focused work and so on.

In this episode, I’ll talk about 
* What Sleep Chronotypes Are
* Are you a night owl or an early bird?
* Benefits of knowing your sleep chronotype
* Aligning to your sleep chronotype

What Are Sleep Chronotypes?

Feeling tired all the time has a massive impact on your mood, work performance, motivation to exercise, and willingness to get out and socialise.

We hear a lot about sleep hygiene and pre-bed routines to work out how to sleep better, but nobody is talking about chronotypes.

Chronotypes are what make us unique. Specifically, your chronotype is the behavioural manifestation of your circadian rhythm (also known as your ‘body clock’), such as when you prefer to sleep and when you are most alert and energetic.

Your natural rhythm also affects the timing of other events in your body like hormone release, meal timing, exercise timing and bowel movements.

In the dawning era of personalised healthcare, we are realising that the old, general rules like “you must get 8 hours of sleep per night” or “we should go to bed by 9pm” are not true.

The truth is – sleep is personal. You are unique in terms of your sleep needs. Emerging evidence suggests that there is a strong genetic component to sleep chronotypes, and that variations in chronotypes might have evolved in hunter gatherers who took turns sleeping so there was always someone to keep watch.

And once you know your needs, certain elements of your lifestyle affect your sleep and should be considered as part of the solution.

Are you a night owl or an early bird?

While there are several quizzes available that can indicate your sleep chronotype, your own personal experience is the key.

It can be challenging to identify your chronotype if your body is ‘out of whack’ for example if you are a shift worker, if you are carrying a sleep debt, or if you are going through menopause or acute stress that is affecting your sleep.

A simple way to work it out is to keep a diary over a week or two, perhaps when you’re on holiday, without work stress, deadlines, over exposure to devices or stressful travel to and from work.

During this holiday time, notice when you naturally feel sleepy and record the time.

Complete your usual pre-bed routine and let yourself fall asleep naturally.

Then in the morning, notice what time you naturally wake up, and record the time.

Over a period of days, without the normal external pressures and influences, you will start to see consistent sleep and wake times, and your natural sleep chronotype will be revealed.

Although we often hear the term night owl or early bird, there are four recognised chronotypes in a quiz by Dr Michael Breus, which are:

1. Lion – the early bird who likes to wake up early and be productive in the morning

2. Bear – accounting for about 55% of the population, their sleep and wake times tend to follow the sun

3. Wolf – the night owl, thought to make up 15% of the population

4. Dolphin – tend to be insomniacs

This is just one chronotype classification systems.

Benefits of knowing your sleep chronotype

If you know your sleep chronotype, you’ll be better able to manage your daily schedule and be alert, productive and focused at the right time.

Imagine of you knew how to structure your day so that you could get things done, get enough rest, feel motivated to exercise, and feel energized and at peace – and then have a good night’s sleep? That’s the power of knowing your sleep chronotype.

Sleep has a huge impact on your appetite, exercise and core temperature, so it also affects your ability to lose weight or maintain a healthy weight.

Various studies show that your chronotype is also associated with some of the ‘Big 5’ personality traits. Lions or early birds (‘morningness’) tend to be associated with conscientiousness and agreeableness, while neuroticism and openness, impulsivity, anger, anxiety and using substances tend to be more common in Wolves or night owls (‘eveningness’). The same studies show that morning people tend to do better in school, and evening people might be better at creative thinking and musicality.

Evening people also tend to be less physically active and sleep less during the week, and more on weekends which can lead to a higher stress response, elevated cortisol levels and a higher resting HR which are risk factors for a variety of sleep, metabolic and mental health concerns.

These are trends, not set in stone, because each person is subject to various external influences that might affect their sleep patterns and overall wellbeing.

Having said that, by aligning your schedule with your chronotype, you will more easily reduce adverse outcomes and be more productive, energized and calm.

Aligning your schedule to your sleep chronotype

Once you know your sleep chronotype, how do you align your schedule so that you can optimise focus, sleep, performance, productivity and recuperation?

While I’ll cover some specific hacks and tips in the next episode, these are some general guidelines to start implementing.

A good starting point is to experiment with going to bed at the time that suits you best, for example, 10pm every night.

Once you establish this time, work backwards and start experimenting with pre-bed routines that will help you have a good night’s sleep and allow you to actually get into bed by this time.

When you have a handle on those two things, your wake-up time should naturally set itself, and you’ll start waking up at a set time every day.

From there, you can work with your energy during the day to adjust your schedule if you can.

For example, early risers might have more energy first thing in the morning and so might do better with exercise, detailed thinking work and any sort of focused action-taking early in the day and could try scheduling those things in the morning if possible. You might also find it better to socialise in the daytime or late afternoon rather than at night as you’ll be winding down.

In contrast, night owls who go to bed later e.g. 11pm might have more energy late in the day, and so could need a more relaxed morning, where you ease into the day slowly, leaving exercise, socialising and intense work for the afternoon and early evening.

If you’re an in-betweener, you may find your energy peak is closer to the middle of the day and could prioritise focused work and exercise from late morning to mid-to-late afternoon.

It may be possible to rearrange your work duties to fit with these frameworks.

A key takeaway is that we are all unique, so experimenting is key as is a need to remove the overlay of stressors, overwork and responsibility that often get in the way of us living our best lives.

Summary

Sleep chronotypes are about more than just optimal bedtime, sleep quality and quantity. By understanding and aligning with your sleep chronotype, you can unlock your full potential in terms of productivity, focus, mental health, motivation to exercise, getting your eating right, and maintaining a healthy weight.

Contact me for support with determining your personal chronotype.

References

David A. Kalmbach, PhD, Logan D. Schneider, MD, Joseph Cheung, MD MS, Sarah J. Bertrand, PhD, Thiruchelvam Kariharan, PhD, Allan I. Pack, MBChB PhD, Philip R. Gehrman, PhD, Genetic Basis of Chronotype in Humans: Insights From Three Landmark GWAS, Sleep, Volume 40, Issue 2, 1 February 2017, zsw048, https://doi.org/10.1093/sleep/zsw048

Gjermunds, N., Brechan, I., Johnsen, S.Å.K. and Watten, R.G., 2019. Musicians: Larks, Owls or Hummingbirds?. Journal of Circadian Rhythms, 17(1), p.4. DOI: http://doi.org/10.5334/jcr.173

Tristan Enright & Roberto Refinetti (2017) Chronotype, class times, and academic achievement of university students, Chronobiology International, 34:4, 445-450, DOI: 10.1080/07420528.2017.1281287

Ready to get clarity on your pathway to success?

Understanding who you are and what you need will allow your business to thrive! If you’re truly ready to break old habits and get out of the rut I encourage you to check out the Habitology membership.

Learn more here:

Learn More