How do we fall asleep?

By Dr Alison Bentley, Restonic Sleep Expert

Falling asleep can be the easiest thing to do. Or the hardest. Good sleepers can’t tell you how they fall asleep – they simply go to bed, lie down, switch off the light and fall asleep. But, for poor sleepers, it’s a different story. And it can also go wrong very quickly for periods in a person’s life, with the onset of an acute stress leaving you unable to ‘switch off’ with your mind racing and unable to nod off. So, what controls falling asleep?

Genetics

One genetic factor is whether you are a lark or an owl. Larks go to sleep early and wake early. But their opposites – the owls – cannot fall asleep until much later and need to wake up later to feel refreshed.

It is a waste of time for the owl to try to fall asleep early in the evening. The time to fall asleep is controlled by the hormone melatonin, which is released by the pineal gland in the brain when it starts to get dark. About an hour later the melatonin causes a drop in the body temperature and it is that drop which makes us feel sleepy. In the lark, that drop in temperature happens much earlier in the night than in the owl.

Melatonin is one of the two biological factors involved in helping us to fall asleep at night. The other factor is called the homeostatic force – simply put – the longer you stay awake the sleepier you will get. So, think about your day as a credit card that you spend on as the day goes on.

When you want to go to sleep, that credit card should be maxed out. Your brain should not be able to stay awake an hour longer. If you are struggling to fall asleep, don’t nap during the day – it pays off the credit card a little bit and you may not feel sleepy enough when you go to bed.

Your busyness during the day also helps you fall asleep. There is, however, a difference between physical tiredness and feeling sleepy. Even exercising for two hours a day will not necessarily make you sleepier if you ignore the other sleep factors mentioned above.


Melatonin is one of the two biological factors involved in helping us to fall asleep at night. The other factor is called the homeostatic force – simply put – the longer you stay awake the sleepier you will get

Safe and comfy

To fall asleep, you also need to feel safe and comfortable, and then it is simply a matter of letting go. By that, I mean you need to be able to relax and let the biological sleepiness take over and put you to sleep. That’s easier said than done in some circumstances, however.

If you are stressed or anxious about anything it can be very difficult to still your mind to feel sleepy. So, get your brain into the right shape to fall asleep. Stop working at least 30 minutes before bedtime. Many people need to do something to distract their mind so that the sleepiness can come and allow them to fall asleep.

Do something relaxing – watching television (no, it isn’t stimulating), reading a book or something like that. Relaxation or meditation exercises are also very useful for this process. Falling asleep is not something you can force – you have to get yourself in the right frame of mind and then let it happen naturally.

Being comfortable is also important. It’s difficult to fall asleep if you’re too hot or cold, if your body is not adequately supported by your mattress, or if you have a bad pillow (read more about how to pick the right mattress for your specific needs here).

However, all the relaxation / meditation in the world, and having a great mattress and quiet bedroom, will not get you to sleep if you haven’t got the fundamental biology of sleep right: go to bed at the right time for you after a long day, distract your mind and allow sleep to happen naturally.

Dr. Alison Bentley

Dr. Alison Bentley

Dr. Bentley is a medical doctor with 30 years of experience treating sleep problems in both adults and children. She has a PhD in restless leg syndrome and has worked in private practice, research including academia. She was the founding chair of the Sleep Society of South Africa and has presented at local and international medical and sleep conferences, and in her spare time, she volunteers to build nursery school classrooms. Dr. Bentley believes sleep remains under-researched and aims to improve sleep research and training for doctors. From 2023, Dr. Bentley will be partnering with Restonic SA to share her knowledge and expertise on sleep