How We Fall Asleep

For many people with insomnia, the most difficult thing is actually falling asleep in the first place. Understanding how this process works in healthy people can help you to identify the origin of your problems and work toward solving them. As scientists learn more about it, it is hoped that new treatments can be developed for people with ongoing problems.

The Chemical Processes of Sleep

How we sleep is regulated by a number of different chemicals in the body. There are three main substances responsible:-

• Cortisol - nicknamed 'the stress hormone', this is the main substance our bodies use to stay awake. Over the course of the day, levels decline, leading us to feel more relaxed and sleepy.
• Melatonin - a special signalling chemical influenced by the amount of light we are exposed to, this substance is usually released into the brain in large quantities to trigger falling asleep.
• Adenosine triphosphate - the 'food' through which energy is distributed to cells throughout the body, this builds up whilst we're awake and is released by brain cells at bedtime in order to trigger the separate processes that switch off different areas of our brains.

To understand how falling asleep works, it's important to realise that sleep isn't about switching off the brain, it's about changing which parts of it are active and how they are working. The release of adenosine triphosphate regulates this, but sometimes things can go wrong, meaning that some brain areas don't get the signals they need. This can lead to an inability to stop thinking and relax, even when exhausted.

Muscle Relaxation

The first thing that happens on an easily observed, physical level as we start to fall asleep is that our muscles relax. In order to do this, muscles may first need to work out cramps and knots. This is why you may find your limbs jerking unexpectedly as you doze off. Don't be alarmed when it happens - if it's persistent, stretching and massaging sore muscles will help you fall asleep.

The relaxation of muscles can lead to a sensation of losing control, which is why we often imagine we're falling just as we start to fall asleep. This can trigger panic in some people. You may dream that you're falling and keep snapping back into wakefulness as you fear hitting the ground. The best way to resolve this is to teach yourself to associate the feeling with something safe and pleasant. Imagine you're falling into a big fluffy bed and your dreams may become less alarming.

Subjective Sleep Sensations

Just as falling asleep triggers a relaxation of the muscles, it also leads to a decrease in nerve signalling - fewer messages are passed around the body. This includes a decrease in brain wave activity. You may be aware of your thoughts slowing down and may find it hard to keep hold of a thread in those thoughts. Resist the temptation to recover that thread, which would lead to you struggling back to wakefulness. Tell yourself it doesn't matter and that now is a time to let go.

As sleep develops, the body temperature naturally drops. This is why it's important to be warm in bed. If you're not properly insulated, your body can notice the cold and panic, propelling you back to wakefulness. At the other extreme, if your bed is too warm, your body may refuse to enter sleep properly because it is unable to cool itself in the usual way.

Falling asleep naturally slows metabolic processes including digestion. You can make this easier by using the toilet just before you go to bed, and by avoiding spicy foods at bedtime, as they can speed up your digestive system. Warm milk, because it relaxes your insides, can have a real physical effect in terms of helping you to doze off.

Understanding the sleep process is sometimes all you need to fix your sleep problems. Learning to relax and accept sleep, with all the odd changes it brings, can be the key to an untroubled life.