I’m not going to start this guide with a glib statement about the importance of sleep, or the problems of not getting enough sleep.
If you’re searching for help then you already know the problems and you want to do something about it.
This guide is going to dig into the academic research and scientific papers that provide some useful insights into good sleep.
I’d like to make it clear that I’m not a doctor. My experience is as a former journalist for the BBC, where I spent many hours trying to separate press release waffle from actual useful data and reliable information.
Here are some key points from our research:
- Most studies say adults need 7-9 hours sleep, but most people achieve more like 6.5 hours.
- A regular routine can help you sleep better, but most of the research refers to having a routine throughout the day rather than in the few minutes before you go to sleep. Eating a gut-busting meal at 10pm once a week probably isn’t a good idea.
- The research we’ve read on electronics and blue light before bed is a bit mixed. It won’t do any harm to cut it out, but it’s not the slam dunk we thought it might be. A big risk is your phone distracting you enough that you get a late night!
- A period of mindfulness meditation before you go to bed is worth a go. There are free videos and training courses online that we link to below. It might be outside of your comfort zone (I would struggle to take it seriously) but large trials have been done and had some good results.
- Perhaps obviously, a noisy environment gives you a worse night’s sleep. Evidence has found that both earplugs and eyemasks can improve sleep, but only if you find them comfortable.
- Complete darkness is ideal for good sleep. We will look at a few ideas for achieving it.
- There are various theories about the best room temperature for sleeping. There isn’t one single temperature that everyone agrees on. However, the most convincing research is the one that says that you need to figure out what the best temperature is for you, and then do your best to maintain it.
- Keeping a window open can help with sleep as it stops carbon dioxide building up (which can disrupt sleep). However, it’s very much a double-edged sword, as the extra noise from having the window open cancels out the benefits of fresh air.
- Music or other noise can be beneficial if it drowns out noise that might wake you up. However, the idea of music relaxing you enough to send you to sleep is much less convincing.
- Napping in the day isn’t a bad idea. It’s not likely to stop you getting to sleep at night. In fact, good sleepers are more likely to also nap in the day.
- If you can’t get to sleep at night, your best bet is to give up after 20 minutes, leave the room and come back half an hour later. Don’t watch TV or eat anything. (This one is based on one expert’s advice rather than an academic paper).
- Exercise during the day can help you sleep better. However, this is another one which wasn’t quite the slam dunk that I hoped. Some evidence is positive but other evidence is a lot more muted.
- Cutting out caffeine, alcohol and smoking are worth a go. Sorry about that.
- Some foods can help you sleep better, but the evidence is a bit mixed. Magnesium, tart cherries and milk show some promise, but have a read of our summary before you rush to Holland and Barrett. Some of the evidence has a lot of caveats!
Let’s plough on with the details. I hope you find this a helpful guide to better sleep.
How much sleep do we need?
Let’s start with how much sleep we should be aiming for. I’m not doing this to rub it in for those suffering from sleep deprivation. My aim is to look at the science and figure out how far away we are from the optimal level of sleep.
A particularly notable piece of research in this area was published by Hirschkowitz et al. in 2015. It was called ‘National Sleep Foundation’s updated sleep duration recommendations: final report‘.
The study begins by admitting that the ‘nature and quantity’ of research in this area wasn’t good enough to come up with ‘a standard evidence-based medicine meta-analysis for each age grouping.’ So, instead they gathered a ‘multidisciplinary expert panel’.
In other words, they gathered together various doctors, professors and other experts to give their opinions based on their years of work. I would much prefer to quote a study where participants were probed and prodded, but this is the next best alternative.
The conclusions of this panel of experts was that:
- Newborns need 14-17 hours sleep
- Infants need 12-15 hours sleep
- Toddlers need 11-14 hours sleep
- Preschoolers need 10-13 hours sleep
- Teenagers need 8-10 hours sleep
- Adults need 7-9 hours sleep
- Older adults need 7-8 hours sleep
The 7-9 hours figure for adults is used by the NHS, although they use different figures for other age groups and say that a newborn sleeps ‘anywhere between 8 to 16 hours.’
And what about minimum levels of sleep?
Another way to look at it, is to see how little sleep we can get away with before it starts doing us harm.
A useful academic paper on this topic was published by Dawson, Sprajcer and Thomas in 2021 in a journal called Accident Analysis and Prevention. It is called ‘How much sleep do you need? A comprehensive review of fatigue related impairment and the capacity to work or drive safely‘.
As you’ll gather, the focus was on how much sleep we need to work safely rather than the impact on our bodies and health. Their work was something of a literary review of 44 existing papers and studies. A key highlight is that ‘a driver or worker might reasonably be ‘deemed impaired’ once the amount of sleep falls below five hours in the prior 24′.
They referenced a number of studies that found that ‘reduced sleep/extended wakefulness’ over 17-24 hours produced a ‘performance impairment’ equivalent to ‘moderate alcohol intoxication’ of ‘0.05−0.10% BAC’. In England, the drink driving limit is 0.08% BAC, which is somewhere in the middle of that range.
In other words, if you don’t get enough sleep then it is a bit like being slightly drunk.
Of course, that doesn’t tell us the ideal level of sleep – just the bare minimum.
Two more studies on ideal sleep duration before we move on
Finally in this section a quick mention for a study that looked specifically at the amount of sleep required by elite athletes (which I am not). This 2021 study by Sargent et al was called How Much Sleep Does an Elite Athlete Need? and was published in the International Journal of Sports Physiology and Performance.
The study worked with 175 athletes in various sports including rugby, football and basketball.
It concluded that ‘athletes need 8.3 hours of sleep to feel rested’ but that most of them weren’t getting anywhere near that (6.7 hours was the average). They also concluded that ‘the most sleep is obtained by athletes who fall asleep between 22:00 and 22:30 hours (7.2 h) or wake up between 09:00 and 09:30 hours (7.6 h)’.
Finally, it’s worth mentioning that the ‘The average nightly sleep duration in U.S. adults (is) (6 h and 31 min)’. I assume the UK is quite similar but haven’t found relevant academic research. If you aren’t getting 7-9 hours sleep then you certainly aren’t in the minority. (Source: An Integrative Review of Sleep for Nutrition Professionals, Golem et al, 2014).
What does the NHS say about sleep?
There aren’t many websites that I trust wholeheartedly, but the NHS website comes pretty close.
If you haven’t found it already, take a look at their guide on How to fall asleep faster and sleep better. Their advice includes:
- sticking to a routine
- avoiding electronics before bed
- meditating and mindfulness techniques
- creating a good bedroom environment
- taking a break from trying to sleep
- exercising
- improving your diet
We’re going to look at some of these suggestions in more depth by looking at the science and studies behind them. Which of them are most likely to make a difference?
1. Sticking to a routine – worth a go but requires commitment!
Having a regular routine is something that appears in pretty much every guide I’ve read to good sleep. But is there are any science behind it? And what constitutes a ‘routine’.
Let’s start with research by Moss et al in 2014 (Is daily routine important for sleep? An investigation of social rhythms in a clinical insomnia population). They worked with 69 people over two weeks and looked at daily routines such as ‘exercise, school or work, recreation, social activities’ rather than a routine just before bedtime.
They found that ‘participants with insomnia and good sleepers had similar levels of activity’ (my emphasis) but that ‘those with insomnia were less regular in their activities’ (my emphasis again).
In other words, people who do the same thing during the day tend to sleep better at night.
A study by Zisberg, Gur-Yaish and Schochat in 2010 in the Sleep Journal looked specifically at the importance of routine for ‘community elderly’. Specifically, they worked with about 90 Israeli Russian-speaking people living in an Israeli retirement community in a study called Contribution of Routine to Sleep Quality in Community Elderly.
The people taking part kept a diary to record their routine each day and then used another questionnaire to record how well they slept.
The conclusion was that ‘Our findings support strong associations between daily routine, as measured by two instruments, and subjective sleep quality’.
In simple terms, older people with a regular daytime routine slept better at night.
These two studies have been an eye opener for me. My assumption was that ‘sticking to a routine’ just referred to the order in which you get ready for bed. For example, I might turn off the TV at 10pm, read for 20 minutes, brush my teeth and then turn off the lights at 10.30pm (well, I don’t brush my teeth for 10 minutes but you get the point).
However, these studies both suggest that daytime routine is important – such as the time you eat meals and whether you do exercise at the same time each day.
This makes some sense to me. We tend to eat at 5pm (as we have young children) but on the odd occasion that we eat out at 8pm I often have a bad night’s sleep. Meanwhile, my stepfather always eats his evening meal at 9pm and still manages to sleep well.
These examples are just an anecdote so let’s not take too much from them and get back to the science.
What about bedtime routines for young children?
This guide is mostly focused on helping adults sleep better but there is a significant area of research around good sleep in young children. This has a particular interest for me, as it was a restless newborn that prompted my 18 months of awful sleep, followed by several years of lighter sleep than I would like.
Mindell and Williamson explored this in a 2018 research paper called Benefits of a bedtime routine in young children: Sleep, development, and beyond. Their definition of a bedtime routine was ‘the predictable activities that occur in the hour or so before lights out, and before the child falls asleep‘.
They found that ‘simply following the same general daily routines in early childhood has been associated with increased sleep duration’ and that ‘a regular bedtime routine is particularly beneficial for multiple aspects of early childhood sleep’.
Of course, this doesn’t necessarily apply to adults as well so take it with a pinch of salt.
2. Avoiding electronics before bed – a mixed picture
Bartel, Scheeren and Gradisar studied this topic and published their work in 2018. The study was published in the US and was called ‘Altering Adolescents’ Pre-Bedtime Phone Use to Achieve Better Sleep Health‘.
They told 63 teenagers that they had to stop using their phones for one hour before bed for one school week (one wonders how this went down with the teenagers). The study group was aged 14-18.
They found that the average person slept for 21 minutes longer, partly because they turned their lights off earlier (presumably because they got bored of reading a book).
My takeaway from that study is that the mobile phones were providing a distraction from sleep.
Is blue light the enemy of good sleep?
And what about the blue light from screens that you have probably heard about?
A detailed summary of the available evidence on this was published in 2022 by Silvani, Werder and Perret in Switzerland. It was called ‘The influence of blue light on sleep, performance and wellbeing in young adults: A systematic review’.
The theory is that the light on electronic devices ‘has a wavelength which may influence our circadian rhythm and cause bad sleep’.
The review produced slightly less neat results than you might imagine. Half of the studies found that blue light led to people sleeping less. ‘Slightly less than half’ found that people took longer to get to sleep.
At one point in the summary they say that: “Sleep quality, sleep duration, and sleep latency did not seem to be systematically affected by blue light exposure.”
In other words, some studies said blue light was affecting sleep whilst others said it wasn’t.
Based on that, I would say that it’s certainly worth trying to cut out screens before bed – but it’s not a slam dunk.
There was another curious side to the study, where they looked at the positives of blue light.
They concluded that “A majority of studies found positive effects such as an increase in cognitive performance, alertness and reduced reaction times.”
The study points out that sportspeople may actually be more alert and less likely to get injured with the help of blue light.
3. Mindfulness meditation techniques to help with sleep
So, what exactly is mindfulness meditation?
According to an NHS guide, mindfulness involves ‘paying attention to what is going on inside and outside ourselves, moment by moment’.
And what does this actually mean? I must admit that I am amongst those who prefer to call a spade a spade (rather than a ‘metallic underground discovery device’) and immediately glaze over at this sort of thing. If you sent me on a mindfulness training course, I’d be the one giggling at the back and trying not to break wind during the quiet bits.
In practical terms, mindfulness might involve (according to the NHS):
- Deliberately noticing how things feel, such as ‘air moving past the body as we walk’
- Trying new things, such as ‘sitting in a different seat in meetings’ so you ‘notice the world in a new way’
- Naming feeling and thoughts, by saying things like ‘this is anxiety’
The idea is that you do this at specific and regular times, rather than constantly floating around as if you are sat on a cloud.
In regards to sleep, the idea is that you sit silently before bed and do things such as ‘paying attention to thoughts, sounds, the sensations of breathing or parts of the body, bringing your attention back whenever the mind starts to wander‘.
If you are like me, then you may be rolling your eyes and concluding that this isn’t for you.
However, it’s worth taking a lot at the science first as some work has been done to assess if mindfulness meditation is total hippy nonsense or a useful technique for sleep.
What does the science say about mindfulness meditation?
Let’s start with a study by Rusch et al, which was published in 2018 under the title of ‘The effect of mindfulness meditation on sleep quality: a systematic review and meta-analysis of randomized controlled trials’. It was published in the Annals of the New York Academy of Sciences, for the benefit of anyone keeping notes.
This study was a summary of the existing research, which pulled together data from 18 trials involving more than 1600 people.
In a rather understated way, it concluded that ‘there was moderate strength of evidence that mindfulness meditation interventions significantly improved sleep quality compared with nonspecific active controls at postintervention… and at follow-up’.
In other words – yes, mindfulness techniques will probably help you sleep better. It’s not a cast iron guarantee and has ‘moderate strength but such things don’t really exist in scientific papers. I’d say it’s worth a go.
A mindfulness trial that you can try at home
Let’s dig into one of the bigger and more interesting studies of mindfulness to help you sleep. We’ve picked out one by Black et al from 2015 with the snappy title of ‘Mindfulness Meditation and Improvement in Sleep Quality and Daytime Impairment Among Older Adults With Sleep Disturbances – A Randomized Clinical Trial’
The study was with people aged 55+ and took place over a year.
Half of the people taking part were given a training course on Mindfulness Meditation (you can see the courses for yourself for free on this university website).
This involved things like “mindful sitting meditation, mindful eating, appreciation meditation, friendly or loving-kindness meditation, mindful walking, and mindful movement.”
The other half of the group was given a course which covered more established tips on sleeping well, based on guidance from the National Sleep Foundation.
The outcome was that ‘mindfulness meditation appears to have a role in addressing the prevalent burden of sleep problems among older adults’.
In fact, the mindfulness course ‘resulted in improvement in sleep quality at postintervention relative to a… standardized…program’
In other words, the mindfulness course worked just as well as the more established sleep training course.
4. Creating a good bedroom environment
A ‘bedroom environment’ includes a lot of different things and it’s the one I have spent most time thinking about on this website. We’ve written guides on mattresses, bedding, duvets, pillows and so on, all of which can make a difference to how well you sleep.
We won’t focus too much on those products, as we’ve covered those in other guides, but we will look at four other areas that are mentioned in the NHS guide to good sleep. Which of these are important – according to the science – and which are less so?
- Earplugs and other things to help reduce noise
- Keeping the room dark through good curtains and blinds or eye masks
- Having a cool and well ventilated room
- Listening to gentle music or white noise
Earplugs and reducing noise
Honestly, I’ve never got on well with earplugs. I think it’s just they way they feel along with the fear that I’ll miss hearing one of the children calling for me in the night.
But don’t let my mild prejudice and bias get in the way. Let’s see what the science says.
Most of the research on earplugs has been on their use in hospitals, particularly where people are in intensive care.
A study by Richardson et al in 2007 called Earplugs and eye masks: do they improve critical care patients’ sleep? worked with 64 patients in critical care.
Half were given earplugs for noise and eyemasks to keep light out. They concluded that ‘many found they improved sleep’ although ‘Mixed reports were found with the interventions from very comfortable to very uncomfortable’.
In other words, the patients slept better but some found the earplugs and eyemasks too uncomfortable.
Another study just looked at earplugs by using noisy recordings (they did this so they could say that the amount of noise was consistent). It was carried out in 1999 and was called ‘The Effect of Earplugs on Sleep Measures During Exposure to Simulated Intensive Care Unit Noise’ by Wallace et al.
The number of people taking part was small but they found that the noise did indeed wake people up (no great surprise there!) but that the earplugs ‘produced a significant decrease in rapid eye movement latency and an increase in the percentage of rapid eye movement sleep’.
Let’s unpack that fairly dense sentence!
REM latency is the time it takes to get from falling asleep to reaching a deeper sleep where you start having dreams. The study found that wearing earplugs got people into this deeper sleep quicker. You could concluded that is a good thing.
What type of sleep is best?
One curveball to throw into the mix is this from John Hopkins Medicine:
“Though REM sleep was previously believed to be the most important sleep phase for learning and memory, newer data suggests that non-REM sleep is more important for these tasks, as well as being the more restful and restorative phase of sleep.”
So, are we to conclude that earplugs will help us get to better sleep or not?
For what it’s worth, my understanding is that they can help and are worth a go. The study mentioned above was carried out at a time when REM sleep was seen as the most important thing, so they were specifically looking for that. Had they been looking for improvements to other phases of sleep, they may well have found them as well.
One other study worth a mention is by Caddick et al from 2018 called A review of the environmental parameters necessary for an optimal sleep environment. We will refer to this one a few times, as it’s a good one.
On the topic of noise they found that ‘all forms of noise in the sleep environment should be reduced to below 35 dB’ to create ‘optimal characteristics for the sleep environment’. According to Yale University, a whisper is 25db and a ‘suburban area at night’ is 40db.
Does a dark bedroom help you sleep better?
And what about having a dark room? We mentioned in the last section that eye masks appeared to improve things in one study, but it was bundled in with earplugs. Anyone who remembers experiments at school will remember the importance of only having one variable.
Also, eye masks can feel quite odd. I’ve tried them myself and didn’t get on with it at all. If anything, it kept me awake. However, as I’ve said several times, let’s not worry about my anecdotes and focus on the science and evidence that is available.
Let’s jump back to the study by Caddick et al mentioned earlier. They concluded that ‘The circadian rhythm is reset by exposure to light through the eye’ and that ‘Complete darkness is optimal for sleep’.
Achieving complete darkness is difficult. If you’ll forgive another bit of anecdotal advice, I’ll give you my top tips from years of trying to get my children’s bedrooms dark (as well as some shift work).
My experience is that thick cardboard is the best thing available. Blackout curtains and blinds are good, but a little bit of light always sneak round the edges and your eyes soon adjust.
I’ve used big sheets of cardboard (from the box of a big TV etc) and have cut them to exactly fit our recessed windows. They wedge in nicely if you are talented with a craft knife. If you are still getting light sneaking in then a thick duct tape also helps.
Does it look great? No, of course not. But desperate times call for desperate measure and if you do it well then it can be taken down each day.
Room temperature – get it right for you, rather than aiming for a magical perfect number
On the topic of room temperature, Caddick et al give a rather broad suggestion that ‘optimal ambient temperature varies based on humidity and the bedding microclimate, ranging between 17 and 28 °C’
A Chinese study looked at three possible room temperatures to see which is best: 17 °C, 20°C and 23°C. It was called Investigation of sleep quality under different temperatures based on subjective and physiological measurements and was by Pan, Lian and Lan (2011).
Their results were curious. When they asked participants which of the three temperatures helped them sleep better, they said 20 degrees Celsius. However, when the researchers looked at various measures of good quality sleep, they found that 23 degrees Celsius was the best.
Here’s the key section of the report:
The subjective results show that 20°C (68.0°F) was the most comfortable temperature for the waking state and 23°C (73.4°F) was the most satisfactory temperature for sleeping. The objective results show that at 23°C (73.4°F), the relative power of the sleep band was the highest, the duration of sleep onset latency was the shortest, and the slow-wave sleep was the longest. All these results were highly consistent, indicating that sleep quality was highest at 23°C (73.4°F).
This 23 degrees temperature is significantly higher than I would have thought would be ideal so I kept digging to see if other studies said the same thing.
Further research on room temperature
The best summary I’ve found into available evidence of bedroom temperatures comes from Strøm-Tejsen et al and was called ‘The effects of increased bedroom air temperature on sleep and next-day mental performance.
Their summary quotes several studies before concluding that there isn’t a perfect temperature that everyone can agree on:
‘There is thus no consensus on the optimal ambient bedroom temperature but most of the evidence suggests a moderate temperature (20-26°C) and that a warmer or colder temperature can affect sleep negatively.’
Their study instead focused on whether we sleep worse when the temperature is higher or lower than our personal preference. They concluded that ‘There was a tendency for the subjects to feel more rested and to experience better well-being the day after sleeping at their normal preferred bedroom temperature’
My initial reaction to this was ‘well, obviously!’. It seems quite unsurprising that we will sleep better if we are comfortable.
However, it is useful as it clarifies that the most important thing is that you feel comfortable at night, rather than sticking to a rigid rule that everyone sleeps better at a particular temperature.
This aligns with our research into mattresses. Generally, people find memory foam mattresses to be slightly warmer than pocket spring mattresses (see our comparison of memory foam v pocket spring for details on the science). So, if you prefer to be warm and cosy, memory foam may be ideal for you. If you like to keep cool, I would probably avoid it or at least go for one with a fancy design that aims to keep you cool.
What about fresh air at night? Does that help you sleep better?
The Caddick et al study also mentioned air quality and found that ‘Exposure to reduced levels of O2 and elevated levels of CO2 can lead to sleep disruption’.
In other words, stale air disrupts your sleep whilst fresh air helps you sleep.
This is backed up by another study called Associations of bedroom temperature and ventilation with sleep quality by Xiong et al (2020). Here’s what they found:
‘Deep sleep percentage was negatively related to bedroom CO2 concentration, with a 4.3% decrement for every 100 ppm increase in the overnight mean CO2 concentration. The deterioration in subjectively evaluated air freshness was associated with poorer self-reported sleep quality.’
Let’s not worry to much about what a ‘4.3% decrement’ looks like. The key point is that as the room filled up with Carbon Dioxide and the Oxygen level dropped, the quality of sleep decreased. Of course, the main reason that the Carbon Dioxide level increased was due to the sleeper breathing in a closed room.
The obvious way to control this is by opening a window when you sleep. You may be asking if anyone has studied whether or not you should open a window at night…
Thankfully, a 2021 study looked at this very specific question. It was called ‘Effects of window opening on the bedroom environment and resulting sleep quality’ by Liao et al.
It studied 27 people, over four nights and measured various things such as carbon dioxide and sleep tracker readings as well as asking people how well they slept. Unsurprisingly, those with open windows had to put up with more noise but those with closed windows had warmer rooms and higher carbon dioxide levels.
The results were a bit of a mixed bag and not all that surprising.
Having the windows open made people feel ‘fresher’ but because of increased noise they felt ‘less rested’ and experience ‘a worse mental state and well-being…and poorer sleep quality’ than those with a closed window.
I also find my hayfever is worse if the window is open and can’t bear hearing the blind banging against the wall…but that’s just me. Another factor of course is that you might not want your window open if you sleep on the ground floor and are worried about security!
Can music help you sleep better?
And what about music? Does that play a role in helping us sleep? Or even white noise?
Dickson and Schubert produced a summary of the available evidence in a paper called ‘How does music aid sleep? literature review’ (2019).
They came up with theories about why music might help with insomnia and looked at which actually made a difference. The strongest evidence was that music could help improve sleep by ‘masking, obscuring noxious background noise with music’.
There was ‘mixed levels of support’ for the idea that you will sleep better because it offers ‘Relaxation, distraction and enjoyment’.
In other words, there isn’t much evidence that listening to music will make you sleepy by helping you relax or forget about your worries. However, it might drown out the sound of your neighbours having an argument.
5. Should you nap during the day, and what time should you go to bed for the best sleep?
The scientific research on this specific question is a little trickier to find than some of the other areas we have looked at so far.
One study worth digging into is by Birling et al in 2020 (Is insomnia disorder associated with time in bed extension?)
They worked with more 300 people, about half of which were ‘good sleepers’ and half of which were ‘insomniacs’.
They found ‘no evidence that absolute extension behaviors (i.e., getting to bed earlier, getting out of bed later and napping) were associated with insomnia.’
Their conclusions on napping are perhaps surprising. They found that ‘Napping is actually more frequent among good sleepers than among insomniacs’. In other words, there isn’t much evidence that you won’t sleep at night if you have a nap in the day (within reason of course, I wouldn’t be napping an hour before bedtime).
How long should I stay in bed if I can’t sleep?
I’ve heard plenty of anecdotal advice about how long you should try to get to sleep before giving up and doing something else.
The best advice I’ve found is a Web MD article. It doesn’t reference academic research, but it does seek advice from ‘Michael Perlis, PhD, director of the behavioral sleep medicine program at the University of Pennsylvania.’
His advice is that you should try to sleep for about 20 minutes. If that doesn’t work, leave the room for at least 30 minutes (I appreciate it’s not always easy to leave the room if you want to avoid waking others up). Have a drink of water if you want but don’t eat anything. Don’t switch on any screens but try ‘reading…listening to music….meditating…experimenting with deep-breathing techniques’ or ‘playing a repetitive game’ such as Sudoku.
As I said, this advice isn’t backed up by academic research but it’s the best that I’ve found.
6. Exercising to help you sleep
What about exercise? My aunt likes to say ‘they’ll sleep well tonight’ if she sees our children running around but is there actually a correlation for adults between exercise in the day and sleeping well at night?
Lowe et al carried out a review of the available evidence in 2019 (‘Does exercise improve sleep for adults with insomnia? A systematic review with quality appraisal‘).
Here’s the summary: ‘we tentatively conclude that exercise can have a beneficial effect on sleep, with differential treatment effects being observed for insomnia disorder and insomnia symptoms. The clinical implication is that physical exercise could represent an alternative or complementary approach to existing therapies for sleep problems‘.
The word ‘tentatively’ is doing a lot of work there. They suggest there is a link between exercise and good sleep but don’t declare it the ultimate answer (although to be honest, academics nearly always take a cautious approach and propose more research).
Banno et al came to similar conclusions in a 2018 study of previous trials called (spoiler alert!) Exercise can improve sleep quality: a systematic review and meta-analysis.
The looked at nine studies with more than 500 people taking part.
I’ve read their paper a couple of times now and the key line is that ‘exercise can improve sleep quality without notable adverse effects in patients with insomnia’. However, they admit that most of the trials they looked at had a‘high risk of selection bias’.
7. What about diet? What foods might help you sleep better?
Finally, let’s look at the links between food and sleep. This is an area which I suspect is highly likely to be full of quackery and anecdote. After all, a manufacturer of a particular type of food will be keen to push the slightest whiff of evidence that their product might help you sleep better.
A pretty significant amount of research has been done into this area.
One of the most thorough academic papers I’ve read on the topic is a 2014 paper by Golem et al called An Integrative Review of Sleep for Nutrition Professionals.
Some key findings from that paper include:
- Caffeine: ‘Even a small amount of caffeine consumed regularly was correlated with disruption in sleep duration, onset, and perceived quality’. So, switch to decaf and see if that helps.
- Smoking: ‘Smoking has been associated with disturbed sleep architecture, sleep fragmentation (waking multiple times during a nocturnal sleep session), increased sleep latency, and shorter sleep duration’. As a reminder, sleep latency is the time it takes you to get to sleep. I appreciate giving up smoking is a bigger deal than switching to decaf coffee, but bad sleep may be a good motivation.
- Weight loss: ‘Improvements in sleep duration have been observed with weight loss, and reduced weight status is associated with healthy changes in sleep patterns’. Note that they are saying people who sleep longer tend to lose weight rather than suggesting that you should lose weight to help you sleep better. In another section they say that ‘inadequate sleep may be a risk factor for type 2 diabetes’. I appreciate that may not be helpful or encouraging, but this guide is just about presenting the science rather than sugar coating it (no pun intended). On the other hand, they also say that ‘Short sleep duration in adults is associated with consumption of an increased percentage of daily calories from fat and snacks’. This finding does suggest that if you eat less snacks and fatty foods then you will sleep better.
- Alcohol: ‘Consumption was significantly higher in adults sleeping <6 h/night than in those with longer sleep duration’. In other words, people who drink alcohol tend to get less sleep.
Are there foods that can help you sleep?
Other studies have looked at the role of different foods that might help sleep.
Arab et al examined ‘The Role of Magnesium in Sleep Health: a Systematic Review of Available Literature’. They found ‘an association between magnesium status and sleep quality (daytime falling asleep, sleepiness, snoring, and sleep duration) according to the observational studies, while the randomized clinical trials showed an uncertain association between magnesium supplementation and sleep disorders.‘
In other words, the results were mixed. Observational studies – where they asked people what their experiences were – showed that people thought they had slept better with magnesium. However, randomised clinical trials (which should theoretically be less prone to bias) had ‘an uncertain association’.
Meanwhile, Pereira et al looked at foods that contain melatonin to see how they help with sleep (Influence of Dietary Sources of Melatonin on Sleep Quality: A Review, 2019). They looked at 190 studies, which is a pretty wide review.
They found that ‘there have been very few randomized placebo-controlled studies on the effects of consuming foods containing melatonin on sleep quality’. In other words, the quality of the available research isn’t ideal.
However, they did say that ‘the consumption of milk and sour cherries, sources of melatonin, may improve sleep quality’.
