Sleep is important. More than you may think. Restorative sleep has a major impact on performance and eating behavior, even if you aren’t aware of it.
How does a lack of sleep cause us to overeat?
To understand how lack of sleep can cause us to overeat you first need to understand the point of sleep, and maybe unsurprisingly it’s all to do with our brain. Here’s the science.
There’s a region in our brain that contains an arousal system. This region is responsible for releasing chemicals like dopamine, serotonin and norepinephrine; these chemicals help to keep us in a state of wakefulness and alertness. Our brain also contains a sleep centre. When it’s time to sleep this sleep centre sends signals to the various parts of the arousal system to shut them down.
What’s important here is that both the arousal system and the sleep centre inhibit each other. When one is active the other is shut down.
Think of the Chuckle Brothers.
‘To me, to you’, ‘To me, to you!’
You get the idea.
As both being asleep and awake are both stable states there has to be a signal strong enough that flicks the switch that allows us to go to sleep and wake up. This signal is strongly thought to be another chemical called adenosine.
Adenosine builds up in our brain when we are awake and builds up even faster when we are pushing ourselves, or exerting intense effort i.e. physical training. As adenosine builds up throughout the day it begins to inhibit the function of the arousal system and thus causes us to feel sleepy and tired, eventually causing us to fall asleep.
This is where we need to monitor our caffeine intake, especially at night. Caffeine works by blocking the actions of adenosine. This is why it’s not recommended to have caffeine too close to the time when you are due to go to sleep. It can lead to a bit of a vicious cycle.
You have a coffee half an hour before you go to bed, you then can’t sleep as the caffeine is stopping adenosine from doing its work to send us to sleep. You wake up having got very little sleep feeling groggy and tired, you have a coffee first thing in the morning to try and wake you up, and so the cycle continues. Day after day.
Common sense should tell you that this is not a good thing. Whilst we sleep, our brain clears excess adenosine and other waste products so by morning wakefulness is restored and we are ready to attack another day. The restorative processes that happen during sleep cannot be undervalued. They are so important for optimal functioning of the brain, and trying to alter or interfere with them, for example with caffeine, will eventually lead to the poor performance of various brain functions.
Lack of sleep not only impairs various cognitive functions, i.e. think of how hard you find it to concentrate when you are tired, it also increases the brains responsiveness to food and its ability to detect our energy status. The brain is basically telling us that we are hungry when we are not, it is priming us to overeat by trying to overcome a negative energy balance (a calorie deficit) that isn’t really there.
Basically when we don’t sleep enough our brain thinks we need more energy, which then activates the our food reward system and causes us to eat more without actually intending to and more often that not without us even realizing it.
So how much sleep do we need?
The simple answer is as much as you need to feel restored.
If you wake up after 6 hours sleep and feel terrible and miserable you likely need more sleep. Get it if you can.
One thing to note is that all the sleep guidelines you see are based on averages from population studies. The problem is that how much sleep you personally need could, and will be, completely different to someone else. So rather than follow a rigid guideline of how much sleep you should get, find out how many hours of sleep works for you on an individual basis. If you get 6 hours sleep and wake up feeling fresh and fully rested you may not gain anything from sleeping more. But if you wake up after 6 hours and feel terrible and miserable you likely need more sleep.
There are five simple steps you can take straight away to move you further towards restorative sleep.
1. Spend enough time in bed. It may be all you need to feel rested.
2. Make sure your bedroom is completely dark at night.
3. Try to keep your bedroom as cool as possible.
4. Only use your bed for sleeping and sex. Not for watching TV or working on your laptop.
5. Avoid caffeine late at night.
I’ve not even touched on Circadian Rhythm yet and how that helps to regulate both our cognitive behavior and eating behavior, or how technology can undermine our sleep quality. I’ll save that for next time.
On a more serious side note if you do suffer from a condition that restricts sleep quality such as sleep apnea, it’s important that you seek professional help. It can be treated and in doing this you will take some big steps to improving your health and quality of life.