Analysis: researchers have found that sleep trackers are often only accurate
38% of the time
By <https://theconversation.com/profiles/matthew-reid-1190405> Matthew
Reid, <https://theconversation.com/institutions/university-of-oxford-1260>
University of Oxford
An estimated
<https://www.nhs.uk/live-well/sleep-and-tiredness/why-lack-of-sleep-is-bad-f
or-your-health/> one in three people report regular sleep complaints so it's
hardly surprising people are more concerned than ever about getting enough
sleep. This blossoming interest has seen an explosion of sleep trackers
which measure how many hours of sleep you get each night.
As we sleep, we go through cycles of "deep", "light" and "rapid eye
movement" (REM) sleep. The "deep" portion of our sleep is mainly what leaves
us feeling refreshed the next day. Most sleep trackers are a watch worn on
the wrist, and work by monitoring your body movements as you sleep to
determine how much time you probably spent awake versus asleep. Some devices
also look at heart rate changes during sleeping to estimate how much time
you spent in each sleep cycle.
Despite their popularity, only a few studies have investigated how accurate
sleep devices are. So far, research has found that compared to
polysomnography tests - which experts use to diagnose sleep disorders -
sleep trackers are only accurate
<https://pubmed.ncbi.nlm.nih.gov/31154154/> 78% of the time when identifying
sleep versus wakefulness. This accuracy drops to
<https://pubmed.ncbi.nlm.nih.gov/31154154/> around 38% when estimating how
long it took participants to fall asleep.
Polysomnography tests are the most accurate because they track a person's
brain waves, heart rate, breathing, blood oxygen levels, and body and eye
movements during sleep through electrodes attached to the skin and scalp.
Analysing brain wave patterns is the only definitive way of knowing whether
someone is awake or asleep, and to know what stage of sleep they're in.
But since sleep trackers are worn on the wrist, they make their estimates of
nightly sleep by measuring body movement and sometimes heart rate data. As
we move frequently during all stages of sleep, movement provides few clues
about what sleep stage we're in. Many sleep devices also fail to
differentiate one stage of sleep from another
<https://pubmed.ncbi.nlm.nih.gov/14998254/> based on motion alone.
Given many consumer sleep devices haven't been compared against
polysomnography tests, it's difficult to
<https://pubmed.ncbi.nlm.nih.gov/31621129/> determine their accuracy rate.
Furthermore, the
<https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109647/#:%7E:text=Key%20Limit
ations%20of%20Wrist%20Actigraphy,sleep%20in%20certain%20patient%20groups>
algorithms which companies use to make predictions about sleep are unknown,
making it difficult for scientists to identify whether the assumptions made
by the sleep devices are valid.
Studies also show sleep devices underperform in people with insomnia. People
with insomnia tend to remain very still in bed in an attempt to fall asleep.
But as sleep trackers only measure movement, one study found watches were
unable to <https://pubmed.ncbi.nlm.nih.gov/31621129/> differentiate sleep
from wakefulness in people with insomnia.
Watches that incorporate
<https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6760396/> heart rate data tend
to be <https://pubmed.ncbi.nlm.nih.gov/32215550/> slightly more accurate
when measuring sleep duration because
<https://www.nature.com/articles/s41598-019-49703-y> heart rate fluctuates
during different sleep stages. However, even in devices that do track heart
rate, many experts are still uncertain of their accuracy because of the
limited research on them, and because of the differences between each
device. For example, one study of heart rate sleep trackers showed that two
consumer devices tended to underestimate the amount of deep sleep wearers
obtained by <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6760396/> as much
as 46 minutes.
Sleep anxiety
Ultimately, this leads to the question of whether knowing about our sleep is
actually beneficial to us. After all, one of the best ways to stay awake is
to <https://pubmed.ncbi.nlm.nih.gov/16809056/> try really hard to go to
sleep. It sounds counterintuitive, but we see this clinically in patients
with chronic insomnia, for whom excessive pre-occupation with sleep causes
anxiety and low mood over sleep loss -
<https://academic.oup.com/sleep/article/29/2/232/2708051?login=true&fbclid=I
wAR0aucBM7TITmyS1Ws0Tan33xffKVHQAmNUsJrtwfApRc76_KPlaRCTMuvs> leading to
further sleeplessness.
A study published by <https://pubmed.ncbi.nlm.nih.gov/29989248/> our
research group showed this effect can be worsened by sleep watches.
Participants were given sleep watches and asked to complete measures of
mood, daytime thinking processes and sleepiness at regular periods
throughout the day. However, the "sleep score" given by their watches was
manipulated to show either an increased or a decreased quality of sleep. The
amount and quality of sleep participants in both groups got was the same.
The study found that those who were told they had a poor night's sleep
showed lower mood, difficulties with daytime thinking processes and
increased sleepiness. Those who were told they had a great night's sleep
showed the opposite.
This shows us that data from these sleep trackers could change your
emotional state and concentration levels during the day - even if the
readings are accurate. Given people who experience poor sleep may be more
likely to use sleep tracking devices, this could be a concern as it may
potentially <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6579636/> worsen
mental health issues.
While few studies have examined this link so far, one report highlighted
more patients are seeking treatment for
<https://jcsm.aasm.org/doi/full/10.5664/jcsm.6472?fbclid=IwAR1KxcxhdpG9CSoB-
72R4cOA_o5iVidnDecoeh8-yzRsf-uhkf42WIPx9qw&> perceived sleep difficulties as
a result of feedback from sleep trackers. Even when such complaints are
refuted by a polysomnography test, watches continue to provide a source of
sleep-related anxiety. Since studies have shown
<https://www.tandfonline.com/doi/abs/10.1080/19325037.2020.1767004?journalCo
de=ujhe20.> overuse of wearable devices (such as those used during exercise)
increase
<https://www.researchgate.net/publication/343942681_When_smartwatches_contri
bute_to_health_anxiety_in_patients_with_atrial_fibrillation> health anxiety
and depression, there's concerns sleep devices may have a similar effect.
While sleep devices might be useful for those who have generally good sleep
but are interested in tracking or establishing a better routine, people who
have poor sleep or mental health conditions may want to avoid them. But the
best metric for measuring how good your sleep was is to see how you feel
each day. If you're tired and struggling to concentrate, then going to bed a
bit earlier each night may help you feel more rested - no device necessary.
<https://theconversation.com/profiles/matthew-reid-1190405> Matthew Reid is
a Post Doctoral Researcher in Sleep and Circadian Neurosciences at the
<https://theconversation.com/institutions/university-of-oxford-1260>
University of Oxford. This piece was originally published by
<https://theconversation.com/are-sleep-trackers-accurate-heres-what-research
ers-currently-know-152500> The Conversation.
Analysis: we know how important sleep is for our health and well-being so
here are some simple ways to improve the quality of that sleep
In mental health research, the literature on sleep is vast. Studies have
found that quality and quantity of sleep can impact our mood, anxiety, our
physical feelings and, of course, our health. With mood, this works both
ways. Low mood can impair sleep, but lack of sleep can also influence mood
problems. Everything seems worse when we don't get enough sleep.
So how much sleep do we need? Research shows that 7 to 9 hours are optimal,
but everyone is different. Most people usually feel that they need around 8
hours, whereas others can cope with less, or need more. As we get older, we
can often need less sleep. This is why those teenagers are hard to get out
of bed, as their brains are still developing, and more sleep is needed.
We go through different stages of sleep, and you can even track this on a
smart watch if you are interested. We need different types of sleep for
different reasons. <https://en.wikipedia.org/wiki/Rapid_eye_movement_sleep>
Rapid Eye Movement sleep (REM), usually occurs later at night and is
important for storing memories, for our mood, and we also dream vividly
during this stage.
We don't actually stay in a state of deep sleep for long at night. Deep
sleep is key for physical recovery, memory and learning. When we get enough
deep sleep, we often feel refreshed. Lighter sleep is also very important,
as it promotes mental and physical repair. You can see how each stage of
sleep has a benefit, so if you aren't getting enough sleep, you aren't going
through these stages and giving your body time to strengthen, rest and
recover from a busy day.
So what can you do if you find sleeping difficult? Simple things can make a
huge difference.
The hour before
The hour before is the most important, and has the biggest impact on your
night's sleep. Keeping a diary of this and monitoring your sleep quality
each night for a week can help you work this out, and what works best for
you.
In that hour before bed, are you staring at your phone? Watching TV or on
your laptop or iPad? Unfortunately, these things do not help us sleep as the
light wakes us up and stimulates our brain. Instead, before bed have a hot
bath. Read a book.
Caffeine, nicotine and alcohol
Ensure you avoid caffeine and nicotine after 6pm, as it can stay in your
blood system for many hours and impact your sleep. Avoid alcohol: it can
help you sleep, but it is not a good quality sleep, and you are not going
through the stages mentioned above. Warm milk and herbal teas can be used as
an alternative. Exercise is also good for sleep, but it can keep your body
awake if done four hours before bed. If you do exercise, try doing it a bit
earlier in the day, if possible. Of course, some people can do these things
and still sleep well, but if your sleep is poor, some of these things could
be impacting it.
Sleeping environment
Your sleeping environment is so important. Your bed should be for sleeping.
It should be a nice, dark, comfortable space that you feel relaxed in. Avoid
doing work in bed, or things that are not associated with enjoyment and
relaxation. Also, try not to nap for more than 20 minutes during the day, as
any more than this can disrupt your sleep.
During the night, if you are awake for more than 20 minutes, you should get
up. Go to a different room, so that your bed is not associated with "tossing
and turning". Sit in the dark and try to relax. You can read, have a warm
hot drink (no caffeine!) or do something that you find relaxing. Do not go
to bed until you feel tired. Bed should not be a symbol of worry, so find a
worry chair and go there instead.
Routine
It is also important to try to go to bed and get up at the same time
everyday. Even if you have not slept well all night, get up and try to force
your body into a routine. Using the same technique, if you are awake during
the night, get up and go back to bed when tired, but still stick to the same
bedtime and morning times in between.
This is called "sleep restriction", which is a way of resetting your body
clock and getting back into a good routine of sleep. For example, start with
six hours, such as midnight to 6am. Keep this routine. Get up at 6am even if
you are tired, try not to nap during the day, and eventually your body will
get used to it. When things improve, increase it by 30mins, and keep doing
this until you get the 7 to 9 hours sleep you need
Don't clock watch!
When we think too much about getting to sleep, or how long we have to sleep,
this often makes it harder. It is also important to try not to clock watch
and overthink. Effective techniques like
<https://en.wikipedia.org/wiki/Cognitive_behavioral_therapy> Cognitive
Behavioural Therapy (CBT) can be used to improve this, by challenging
negative expectations and managing worry. Meditation and alternative
treatments like reflexology can also benefit your sleep. Of course, sleep
medication is another option if sleep has really become a problem, but this
is something that should be spoken about carefully with your GP, to weigh up
the pros and cons. Perhaps from this article, you will learn something
simple to try first, that you may not have thought of doing before!
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