Tag: sleep hacks

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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#207 Sleep Hacks for Insomniacs

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Sleep Hacks for Insomniacs

If you’re like me, sleep can be hit and miss at times and getting enough sleep can become a drain that affects your performance and productivity. In this episode, we’ll cover a few sleep hacks recommended by leading neurobiologists that can help you to improve your chance of falling asleep and staying asleep.

In the last episode of this podcast, we discussed sleep chronobiology and its impact on health and wellbeing, along with a few simple tips to identify your chronobiology and how to align your routines to your personal type.

Now let’s get specific with some hacks! Many recent (2022) journal articles have revealed how ocular light exposure – that is, light entering the eyes – affects our circadian rhythms and sleep, endocrine function, and cognitive function, which in turn influence human health and wellbeing.

In this episode, I’ll talk about 
* Evening sleep hacks for winding down at night
* Sleep hacks for falling asleep and staying asleep
* Tips for setting your sleep clock

This conversation is partly based around “melanopic light”, which describes the way that blue light frequencies restrict melatonin production in your body until after dusk, after which time melatonin washes through the body to help you sleep.

The recent advances in our understanding of the relationship between light exposure and sleep have led to the development of new standards and practices. By understanding how different light sources and timing of exposure work, neurobiologists have been able to develop recommendations for improving sleep quality and quantity.

Let’s take a look at some of the hacks that you can use, for free, to improve your sleep.

Evening sleep hacks for winding down

An interesting hack is the recommendation for morning sun exposure (outdoors) which can mitigate any undesirable effects of indoor light exposure (during the day and at night), so that you can wind down more easily and sleep better.

We also need to dim the lights in our houses. Recent advances in our understanding of circadian rhythms means that light manufacturers have been able to produce blue light components so that artificial lighting systems in our homes and offices are very similar to actual daylight.

But while this is great for productivity during the day, it is not so good at night when we want to wind down and fall asleep. In that sense, after sunset, the experts recommend dimming the lights in your home, in the evening at least 3 hours before bedtime. This reduces the amount of light entering your eyes and helps allow the melatonin wash to occur.

This also applies to electronic devices. Televisions, computer screens, tablets or mobile phones all emit blue light and are often close to your eyes, so turning off in the around sunset might help you to fall asleep and stay asleep.

While we’re talking about sunset, one interesting study showed that when you couple daytime outdoor light exposure with early evening light exposure (e.g. sunset), it can help to decrease the sleep disruptive effects of nighttime light exposure.

And if you have bright lights on late at night, you will suppress melatonin, the hormone that helps you relax and feel sleepy, which obviously affects your quality and duration of sleep.

Aside from light, there are other things that can improve your ability to fall asleep and stay asleep.

Food and exercise can affect your ability to fall asleep.

People who are early risers (see episode 206) might do better with an earlier dinner, exercising earlier in the day, and minimising socialising at night so as not to disrupt sleep.

In contrast, people who are night owls (see episode 206) could eat later without disrupting sleep but might need a lighter dinner, and to finish exercise before 7pm so as not to disrupt sleep.

Otherwise, and more generally, alcohol intake at night might help you fall asleep but might wake you up between 1 – 3am.

For some people, a high-carb meal (more specifically, higher in simple carbs) might delay sleep onset – in other words, it takes longer to fall asleep – or cause them to wake up hungry.

Similarly, caffeine or other stimulants after 3pm might disrupt sleep in some people, as it takes 3 – 15 hours to metabolise and excrete caffeine.

A heavy meal at night or overeating at night often disrupts sleep. Either can cause indigestion, heartburn, or simple discomfort before bed or during sleep. That’s because, during sleep, our digestive processes slow down but can also create competition for resources in the body if you have an undigested meal in your stomach.

Eating a heavy meal or too much food may cause you to wake up the next day without an appetite or even feeling heavy or sluggish because you’re still working through last night’s meal.

The remedy for this is simple – and twofold:

1. it takes around 4 hours to digest a meal, so finish eating at least 3 hours before you go to bed, and

2. eat a lighter meal before bed with lots of vegetables, and the right amount of complex carbs, fats and/or proteins for your HealthType.

Sleep hacks for falling asleep, staying asleep and waking up energized

The science shows that inadequate daytime light exposure is as detrimental as too much electric light exposure at night, with both of these having adverse effects on your sleep, circadian rhythms and health outcomes.

So, in order to set yourself up for a good night’s sleep, the experts recommend that you get outdoors and get daytime light exposure within 30 – 60 minutes of waking up, if possible during the day, and also around sunset.

During the day (before sunset), aim for at least 2.5 hours of bright light exposure including your early morning exposure, and another hour in the late afternoon or evening.

In terms of light exposure while you’re asleep, the experts recommend that your sleep environment is as dark as possible. If you do need to get up for the bathroom during the night, the recommended

maximum exposure to light is 10 lux (which is a unit of measure of light). You can download an app on your phone that measures light as a rough guide to help you determine exposure.

That aside, anxiety and worry can add to sleep issues. I have discussed this extensively in other episodes but it’s worth mentioning here – get some help, keep a worry diary and/or get on top of your task list to help you sleep easy at night.

Having some light, fun activities that aren’t too stimulating in the early evening can help you switch off!

Shift workers – a special case

Light exposure for shift workers is still an area of study and a challenge that neurobiologists haven’t yet been able to solve.

At this time, there is evidence that increasing melanopic light levels at work (e.g. office lighting) can improve alertness, as measured subjectively (e.g. questionnaire) and/or objectively, but this requires further study in the shift work population.

In any case, I speculate that even shift workers can create some improvements in sleep, and we will look at that in another episode in more detail.

For now, let’s assume that eating and exercise can be modified to improve the chance of a good night’s sleep, and further, block out curtains and getting the timing of light exposure right might help to create a rhythm that facilitates sleep.

Setting your circadian rhythm

In the previous episode of this podcast I talked about determining your sleep chronotype – in other words – the time you wake up and the time you go to bed. Whether you’re an early riser, a night owl or an in betweener, being consistent with wake and sleep times can help you establish a regular daily light-dark cycle which can further benefit sleep, cognition and health.

And as described earlier in this episode, getting outdoor light exposure soon after waking and again late afternoon can help you to sleep more soundly, and wake refreshed.

Summary

And as described earlier in this episode, getting outdoor light exposure soon after waking and again late afternoon can help you to sleep more soundly, and wake refreshed.

If you want to sleep well, also consider the timing, quantity, and quality of food and exercise in the context of your chronotype – nothing within 3 hours of sleep, and reducing or avoiding alcohol, caffeine, and high glycemic foods or heavy meals.

Think about switching off devices after sunset and dimming your house lights.

There is so much coming out about sleep right now, and today’s summary of research includes a few tips to help you manage your sleep better.

References

Brown TM, Brainard GC, Cajochen C, Czeisler CA, Hanifin JP, et al. (2022) Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults. PLOS Biology 20(3): e3001571. https://doi.org/10.1371/journal.pbio.3001571

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