The Science of Sleep

What Is Sleep and Why Is It So Important?

Ahh, that lovely feeling of floating downstream as you slowly drift off to sleep. Arms and legs get heavy and the mind wanders freely through grassy meadows and alongside peaceful streams...if only it was always like that!

For those suffering from sleep problems, the mysteries of sleep can be enough to keep you awake at night. Lying in bed puzzling over these mysteries will certainly not help bring the sleep we crave. So, what is sleep and what can we do when we can't sleep?

Sleep is surprisingly complex and has important functions that enable us to recover from the stresses and strains of the day. Our brain works hard during sleep breaking down chemicals and toxins to help us get ready for the day ahead.

woman sleeping

The Role of Chemical Messengers

Chemical messengers called neurotransmitters help the brain signal arousal or relaxation.

Serotonin and norepinephrine send signals to keep us awake during the day, making us feel aroused, wakeful and attentive.

Chemical messengers that work in the opposite way include adenosine, melatonin and gamma-aminobutyric acid (GABA).

During the day a chemical called adenosine builds up in our blood making us feel drowsy. While we sleep it gets broken down so that we wake feeling refreshed.

Melatonin (often called the sleep hormone) helps to tell your body when it’s time for bed, making it easier for us to fall to sleep and stay asleep throughout the night.

GABA reduces the activity of neurons in the brain and central nervous system. It increases relaxation, reduces stress and helps induce a more calm, balanced mood.

Our Circadian Rhythm

The circadian rhythm is related to our biological clock and it’s this clock that produces and regulates circadian rhythm.

This rhythm is a natural process also known as your sleep/wake cycle - our brains following a rhythm of being awake during the day and sleeping at night.

It’s the reason why we struggle to sleep when we are jet-lagged, or when we work night shifts and suffer from irregular sleeping habits. It's also why there is a very high rate of sleep disorders in those who are completely blind; without the light cues, it's much harder for our bodies to recognise when to send out those neurotransmitters.

woman lying in bed

The Stages of Sleep

There are four main stages of sleep plus the infamous REM sleep phase.

Stage 1 - This is the “just drifting off stage”. During stage 1 we drift in and out of sleep and are easily roused. Our muscles begin to relax giving that heavy feeling. It's during this stage that people often have unexpected muscle jerks and may feel like they are falling.

Stage 2 - It usually takes between 5 and 15 minutes to move from stage 1 to stage 2. During stage 2 sleep, eye movements stop and brain waves slow down. There are occasional bursts of rapid brain waves called sleep spindles, but mostly everything is quiet during this stage as we start to head into deep sleep.

Stage 3 - This is the first stage of deep sleep, in which our brain waves become very slow, called delta waves. During this stage of sleep, less than 50% of brain activity is made up of delta waves.

Stage 4 - The second stage of deep sleep. During stage 4 sleep more than 50% of brain activity is made up of delta waves. In the past, it was thought that dreaming only occurs during REM sleep, but it looks like we do also dream during deep sleep. When you reach this deep sleep, it’s really hard to wake up from it.

Stage 5 – This is the only stage of rapid eye movement sleep (REM) and most adults have a sleep cycle that takes about 90 minutes and alternates between non-REM and REM sleep. It’s quite different from the other sleep stages as the brain is active and dreams are likely to occur. When we reach this stage, our breathing becomes more rapid and shallow, there's a lot of eye movement (hence the name!) and the muscles in our limbs may become temporarily paralyzed.

Sleep Disturbance

During healthy sleep, we drop down through stages 1,2,3 and 4 and then back up into REM. We then drop down again into a deep sleep once or twice more during the night. Through the night, the amount of deep sleep declines and the amount of REM sleep increases.

If our sleep is disturbed we are likely to drop straight into REM sleep; this feels familiar to anyone who has had problems sleeping – suddenly you drift off into wild and bizarre dreams and wake feeling like you need several more hours of rest after a busy night of dreaming. This is also why it's not really possible to catch up on sleep because it's not the deep, restful sleep that we fall into. We also spend a lot longer in REM sleep if our sleep is disturbed rather than cycling through into deep sleep.

Girl lying down on soft rug

How can we Prevent Disturbed Sleep?

There is now a lot of research showing that weighted blankets are one of the most effective non-medicinal sleep aids and looking at the stages of sleep, it's easy to see why.

In the first stage of sleep, our muscles become heavy but can be disturbed by movements and the feeling of falling. This is where a weighted blanket can help.

The pressure from a sleep blanket reduces muscle movements making it much easier to drift off to sleep. There's also lots of evidence that it helps those with anxiety, stilling both the body and the racing mind. A weighted blanket supports the body's natural sleep processes, promoting stillness and relaxation and helping waves of deep, refreshing sleep wash over us. Bliss!

Woman sleeping under duvet

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