Exactly What IS Sleep?

I was lying awake in bed the other night, thinking to myself, exactly what IS sleep. Why is it so distressing to be missing out?

I know I can’t live without it – I’ve proved that to myself. Sleep is definitely a lot more than just something to do in the middle of the night while everyone else is off in dreamland. So naturally, I Googled.

What happens while we sleep?

Sleep is a jolly busy time for the mind and body, resulting in physical restoration and brain organisation. It’s believed to strengthen the immune system, improve heart and blood vessel health, encourage growth and healing, improve attention, memory and learning, and assist with appetite and weight regulation.1

In short, there’s a lot of stuff happening when we think we’re doing nothing. When things go wrong with the sleep cycle, we can experience problems with both our physical and mental health.

The chemicals that control sleep

Chemicals called neurotransmitters control when we sleep and wake. A whole pile of names with lots of letters – like serotonin, norepinephrine, hypocretin, GABA, acetylcholine, histamine, adrenaline and cortisol – all function to either keep parts of our brains active when we’re awake or assist with muscle relaxation and sedation when we’re asleep.2

When there is too much or too little of these chemicals, the quality of sleep can be affected.

An activated sympathetic nervous system

During my sleep study, it was found I was in a state of hyperarousal throughout the night (and probably the day as well). This means my sympathetic nervous system – fight or flight response – stays activated all the time with adrenaline, noradrenalin, and glucocorticoids coursing through my veins, making relaxation nigh on impossible. Naturally, this has a fairly profound negative impact on my sleep.

What are circadian rhythms?

Circadian rhythms are the body’s internal "clock," responding to both internal and external cues. They impact the release of hormones, eating habits, digestion, and body temperature but are also key in telling us when to fall asleep and when to stay awake.2

Circadian rhythms react to light and dark and are affected by physical, mental and behavioural changes over a 24-hour period. Disruption to circadian rhythms can also have a major impact on sleep.

Phases of sleep

When we do actually sleep, there are 2 main phases, REM (rapid eye movement) and non-REM. In a normal sleeping pattern, REM sleep occurs every 90 minutes or so throughout the night. Typically, adults experience 20 percent of their sleep in REM sleep.1

REM sleep

During REM sleep, there is rapid eye movement and blood pressure, heart rate, and brain activity increase. This is when we are most likely to dream and may well help us learn and create new memories.1

Non-REM sleep

Non-REM sleep has 4 phases. In stage 1, we hover between sleep and wakefulness and can be easily woken. During stage 2, we lose awareness of our surroundings, body temperature drops, and breathing and heart rate slow. Stages 3 and 4 are called deep, or "delta" sleep, where eye movements stop, body temperature drops, muscles relax, and we fall into a deep sleep. Growth and repair processes happen at this time.1

Those of us experiencing one of the many varieties of sleep disorders may well find their balance of REM and non-REM sleep to be out of whack, causing a sense of fatigue when the body hasn’t had the opportunity to restore overnight.

What does the science mean for me?

Personally, I find all this science stuff quite interesting, but at the end of the day, I want to know what to DO about it. It’s all fine and dandy to discover my noradrenalin levels are out of whack, but how do I fix it?

The simple answer is there’s no simple fix. Most people (all people?) want to experience a good night’s sleep, and if it was as simple as avoiding caffeine, nobody would have insomnia.

Taking steps to address prolonged insomnia

While the first step to improved sleep is definitely following good sleep hygiene protocols, if prolonged insomnia continues, it is always worth a visit to your favourite medical practitioner. Investigating physical and psychological causes can lead to an improvement.

Cognitive behavioural therapy has a profound impact on the quality of my sleep. There is no quick fix for hyperarousal, but lots of psychological therapy has most definitely had a positive effect for me. And to cure the many other reasons my body fights sleep at every stage, I have pharmacological sleeping aids. The consequence of all this support is I now spend far fewer nights lying awake wondering, What is sleep?

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