She's also passionate about travel, scuba, and hiking, and loves to spend time outdoors in all types of weather.
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In our last article, we talked about how sleep helps protect our brain as we age. There’s really no question about the value of sleep for longevity[1]. This is one of the most powerful tools you have for improving your healthspan. As we’ve explored in a previous article, the brain removes toxins during sleep, which might otherwise build up and lead to dementia. There are numerous other benefits, from secretion of longevity-promoting hormones like human growth hormone to stimulation of autophagy (the clearance of damaged cells or parts of cells).
But what should you be aiming for? How much sleep do you actually need?
How do we really know how much sleep is enough?
This question is harder to answer than it might look at first. We’ve all heard eight hours bandied about as the right amount of sleep to get. Where does that number even come from? Is it accurate? How can we possibly know how much sleep is the right amount?
Some studies have shown that the fewest health problems accrue to those who sleep seven to eight hours a night, while others have shown that seven to nine is the sweet spot[2]. Sleeping less than that causes a sharp rise in a variety of health problems – but so does sleeping more.
That’s likely true because needing extra hours of sleep can be a sign of a problem with the quality of a person’s sleep. Sleep apnea, for example, causes a person to wake many times throughout the night because they’ve stopped breathing. Although they may not remember being woken up, a person with sleep apnea will tend to feel groggy during the day. They may spend more time in bed, trying to get enough sleep to stop feeling tired. A person like this will report sleeping a lot, but the truth is that they’re hardly getting any quality sleep at all.
How do you know if you’re getting enough slow wave sleep?
There’s really no question about sleep’s value for brain health and longevity. But now a very important question arises. How do you actually know whether you’re getting enough slow wave sleep?
Do sleep trackers really measure sleep?
The most reliable way to track anything is to measure it, and sleep is no exception. Unfortunately, without an EEG (measurement of electrical activity in the brain), the sleep tracker can’t really know for sure what phase of sleep you’re in.
Most sleep trackers really just track movements, and this is at best a way to estimate sleep rather than a way to truly measure it – not to mention that there are often confounding factors, especially if you share a bed with a partner. Adding another source of data, like heart rate, helps to improve the accuracy of a sleep tracker, but it’s still just basically estimating sleep rather than measuring it directly.
If you’re looking to find a sleep tracker that truly measures sleep, the gold standard would be one that uses EEG. Such devices are now available, and collect data via a headband. However, they aren’t cheap, and not everyone wants to invest in something like this. If you’re not prepared to go to that level, then a sleep tracker that measures heart rate is likely to give you more accurate data than one that measures only movements.
Using yourself as a measuring device
Even without any type of tracking, paying close attention to how you feel throughout the day can give you a good idea of whether you’re getting enough quality sleep. If you’re spending eight hours a night in bed, but you’re still tired during the day, it’s possible that your sleep is being interrupted during the night. This tends to result in spending too much time in lighter stages of sleep and not enough in restorative slow wave sleep.
A person who’s truly well-rested will wake up naturally, without an alarm. If you need an alarm to wake up in the morning, then you’re either not getting enough hours of sleep, or the quality of your sleep is not great. If you’re getting less than about eight hours, increasing the hours that you spend in bed should help. If you’re already spending that much time, but you still need the alarm, then you should turn your attention to the quality of sleep. (It’s also possible that your physiology is simply calibrated to need a little more sleep than average, and you’re sleep-depriving yourself by getting only eight hours. You could try increasing it a bit to see if that helps.)
If you find yourself waking up multiple times every night, this is a sign that the quality of your sleep might not be great. It’s important to recognize that waking in between sleep cycles can be a normal part of sleep, and isn’t always something to be concerned over. However, excessive nighttime awakenings can interfere with the quality of sleep. It’s particularly concerning if you’re being awoken during a sleep cycle, rather than in between them.
Remember that sleep cycles are about 90 minutes long; if your awakenings are less than 90 minutes apart, then they’re almost certainly breaking up a sleep cycle, which means your sleep is not high quality. Another way to tell is by how you feel when you wake up. If you’re groggy and sluggish, this is a sign that you’ve been awakened during slow wave sleep, which means that your sleep is likely being disrupted.
12 evidence-based ways to improve your sleep
Sleep is a tricky phenomenon. You can’t really force yourself to sleep – the more you try, the harder it is to get to sleep. What you can do instead is create the right conditions for sleeping. Here are a few science-backed ways to help yourself sleep better, meaning that you not only sleep enough, but get high-quality sleep.
1 – Keep your sleep times as consistent as possible
Yes, even on weekends. Decades of research affirm that the more consistent your sleep times are, the better your health outcomes will be[3]. This certainly doesn’t mean that if you’re sleep-deprived all week, you should just stay that way on weekends too. Instead, whatever time you need to get up during the week, try to adjust your bedtime so that you can wake up when you need to without an alarm. This process starts by getting up at the same time every morning; if you’re used to going to bed late on weekends, you might be a little tired at first.
Keep this consistent awakening time, and start adjusting your bedtime, trying to keep this consistent too. It may take a bit of experimentation for you to find the sweet spot; you can start with going to bed eight hours before your wake-up time, then play around with it until you’re waking up on your own (without an alarm) at the right time. Waking without an alarm lets you know that you’ve gotten enough sleep. Once you find a schedule that works, try to keep your bedtime as consistent as you can, even on weekends – leaving some room for staying up late on special occasions, but keeping those as rare as possible.
2 – Create a bedtime routine
The brain is an excellent pattern-learning machine. If you create a pattern that’s associated with sleep, then your brain will more easily shift into sleep mode when it’s time. Try some kind of routine for the last half hour to an hour before bed, which involves calming activities like reading and/or journaling. You could even try aromatherapy – some studies have shown that inhaling a particular scent every night before bed improves sleep quality[4]. It doesn’t seem to matter too much what specific scent it is; it’s just the consistency of the association that matters.
For similar reasons, try to keep your bed just for sleep; do your chilling and general hanging out somewhere else, like the couch. This keeps the bed associated with sleep in your brain.
3 – Take a warm bath or shower before bed
Studies have shown that taking a hot shower or bath one to two hours before bed can help you fall asleep faster and improve sleep quality, including the amount of slow wave sleep[5]. This is probably because there’s a natural decrease in body temperature close to bedtime. Raising your body temperature externally then causes it to fall afterwards, which mimics this natural drop. For best results, the water should be between 40 and 43°C (that’s 104 to 109°F), and you should stay in for at least ten minutes. This is a great way to start your bedtime routine.
4 – Make your bedroom as dark as you can
Studies have shown that even very dim light at night has a measurable negative impact on sleep[6]. Eliminate all sources of light from your bedroom, including all those little lights on devices that are charging. You can try charging them in a different room, or covering up the little lights with electrical tape. Remember to cover the light on the smoke detector. Get blackout curtains for your window. The more light you eliminate at night, the better you’ll sleep.
5 – Eliminate extraneous noises too
Just like with light, studies have shown that noises at night impact the quality of sleep, even if you think that you’re “used to it.”[7]. Although making the bedroom as quiet as possible is an excellent goal, the unfortunate truth is that we don’t always have control over noises in the environment, and it can be far harder to soundproof our bedroom than to light proof it.
If you can make your bedroom as silent as possible, then this is the ideal. Using earplugs might help to ensure that little noises won’t reach your eardrums. But sometimes it just isn’t realistically possible to eliminate environmental noise from the bedroom. In that case, the best way to eliminate the disruptive effect of noise on sleep may actually be to add more of it – white noise can help to cover up those inevitable little noises that might otherwise disturb your sleep. This can be as simple as turning on a fan or air purifier in your bedroom. It’s important to note that, while there’s some research indicating that white noise can improve sleep, the evidence is of pretty low quality, and not everyone is convinced that it’s effective[8]. We just don’t really have good evidence so far. However, so far there isn’t any solid evidence of adverse effects either, so if you find your sleep is often disrupted by noises in your environment, you could always try using white noise yourself for a few nights to see whether there are positive effects for you.
If you want to get fancy with it, there are even special noise-cancelling earbuds for sleep, which can also play any type of white noise that you choose. These have shown some decent results in preliminary studies in shift workers (who often have no choice but to sleep in noisier-than-average environments), but they’re still not really a perfect solution, and the jury is definitely still out on this one[9].
6 – As much as possible, avoid electronic screens close to bedtime
The light from screens can suppress your secretion of melatonin, the hormone that’s important for promoting sleep. Blue light has the greatest impact, but even yellow or red light has been shown to have an effect – so turning on the yellow-shifting app on your phone really isn’t enough[10]. Similarly, blue-blocking glasses might also be helpful, but are still not as good as avoiding screens altogether – you’ll still be exposed to the brightness of the screen, not to mention the stimulating effect of whatever it is you’re looking at. Ideally, put the screens away at least 30 minutes before bedtime, and longer is better.
7 – Get exercise during the day
People who get moderate to vigorous exercise sometime during the day sleep better at night. The research on this actually isn’t perfect, and there are still people who disagree that starting an exercise program will improve your sleep – but most of the evidence certainly does point in that direction[11]. Not to mention that if there’s another fountain of youth that’s equal to sleep, it’s exercise.
8 – Sleep naturally, without using meds
In a large study done in Finland over more than two decades, the frequent use of hypnotics and/or tranquilizers to get to sleep was associated with double the risk of death[12]. This is probably because, while these meds make you feel like you’re sleeping, they also interfere with sleep architecture, so the quality of sleep is not as good. Taking a sleeping pill might make you look like you’re asleep, but you’re really just knocked unconscious rather than truly sleeping. If you’re finding it hard to sleep, it’s generally better to adjust your environment rather than taking sleeping pills.
There are certain supplements that may help to support natural, healthy sleep. Reviewing these would take quite a while, so we’ll save the specifics
9 – Don’t go to bed hungry
This one is sometimes a little counterintuitive for people, because we’ve been told not to eat too close to bedtime. It’s true that if you eat a large meal right before bed, then you’re probably not going to sleep very well. However, if you’re really hungry in the middle of the night, then your brain will tend to awaken to deal with the situation – interfering with your sleep[13]. People who are fasting often notice that it affects their sleep. While this might be okay short-term for an occasional fast, it’s probably not great if it’s happening consistently.
If you find that you awaken in the middle of the night or very early in the morning and you’re hungry, then you might actually want to try having a snack about an hour before bedtime in order to get better sleep. If the snack is nothing but simple carbs, then you might actually find yourself with a disruptive blood sugar crash (and associated hunger) during the night. A protein-containing snack will tend to last longer – but anything that’s difficult to digest could also tend to disrupt sleep, so don’t pick anything that generally has that effect on your body.
Other opportunities to talk about
10 – Watch out for the half-life of caffeine
Coffee has acquired an unfortunate negative reputation in some health circles. This is not necessarily deserved – coffee, and other caffeine-containing substances (like tea and dark chocolate), actually seem to have a longevity benefit[14]. (We’ll explore this more in future articles.) There are some interesting studies indicating that, in people who use caffeine habitually, abstaining from caffeine doesn’t actually improve sleep[15]. If you enjoy caffeine, you don’t have to stop using it entirely in order to improve your sleep.
However, the timing of caffeine consumption might have an impact on your sleep quality. Caffeine can stick around in your bloodstream for longer than many people realize. The half-life of caffeine is about five hours (although there’s significant variation between individuals), meaning that if you have a cup of coffee, around half of the caffeine is still in your system five hours later, and a quarter of it is still there ten hours later.
Caffeine tends to disrupt sleep. Its greatest effects are on NREM sleep, and it’s known to have the potential to reduce the amount of slow wave sleep. The most common recommendation is to avoid caffeine within six hours of bedtime, but some research suggests that a dose of caffeine six hours before bedtime can still interfere with sleep, so you might want to wait even longer[16]. (For clarity, in this study, the dose used was fairly high – 400mg, which equates to about 3-4 average cups of coffee.)
11 – Watch out for alcohol too
The relationship between alcohol and longevity is complicated – let’s save that for a future article. For now, we’re mainly concerned about alcohol’s effects on sleep. Alcohol is a nervous system depressant, so it might feel like it’s helping you fall asleep. However, it also interferes with sleep architecture, causing disrupted and poor-quality sleep, especially in the second half of the night[17]. This effect may be partly mediated by acetaldehyde, which is a byproduct of alcohol metabolism that’s also a stimulant.
If you do choose to drink alcohol, it’s best to make sure that it’s out of your system before bedtime. This takes about one to two hours per drink. So if you decide to have a drink in the evening, make sure that you’re finished with it at least two hours before bedtime – and longer is better, to ensure that your body is done processing the alcohol so that it won’t interfere with your sleep. (If you have two drinks, you’d need to finish four hours before bedtime.)
12 – Talk to a healthcare professional if you can’t optimize your sleep
If you’ve tried the techniques above, and you still find that you can’t get up in the morning without an alarm and/or you’re tired during the day, even though you’ve been in bed for eight to nine hours – then it’s a good idea to talk about it with a professional, like a functional medicine doctor. It’s possible that your body’s ability to get good sleep is being disrupted by a sleep disorder, such as sleep apnea. The good news is that this can often be treated. For example, there are devices available that people with sleep apnea can use to help to keep the airways open at night, so that they’re able to get good sleep. People often describe these devices as life-changing.
Given how important sleep is to your health and longevity, it’s important to address whatever the issue is so that you can start sleeping better. Optimize whatever you can, and then if you’re still not getting the results that you want, ask for some help.
There’s value in sleep itself
Most of the time, people tend to think about sleep primarily in terms of the benefits that it provides to waking life. Those benefits are indeed many, but sleep is also an interesting state in and of itself. You generally don’t remember your dreams while you’re awake (which is a good thing, because if you did, then it would be very easy to get confused about what actually happened and what you only dreamed about). But they’re still an intriguing experience that you get to have.
You have the opportunity to enter an altered state of consciousness for several hours every night – to lie down and vividly hallucinate, while simultaneously restoring your health. What a delightful opportunity nature has given us. Enjoy it.
