Myths around sleep are keeping people up at night, according to health psychologist Clin. Assoc. Professor Delwyn Bartlett.
Understanding how your sleep changes across the night and throughout our lives, enables us to have realistic expectations around sleep. The most common myths around sleep are that we spend most of the night in deep sleep; waking is abnormal; and dream sleep is deep sleep.
However, these statements are inaccurate. Most of our deep sleep occurs in the first third of the night. The brain tends to take what it needs first. When we have been sleep-deprived, deep sleep is increased. We generally only spend 20% of the night in deep sleep. The brain and in particular the cortex rests with reduced electrical activity.
Most of our sleep is spent in relatively light sleep (45-55%), or Non-Rapid Eye Movement (NREM2 or N2). This is probably an evolutionary response. This light sleep allows for changing our body position and to be aware of any altered environmental factors.
We wake 2-3 times per night which can increase between 5-9 times per night with age – we do not usually remember these wake times. Waking during the night is normal as is the need to change our body positions and check our environment.
Dream sleep, or Rapid Eye Movement sleep (REM) is the opposite to deep sleep being similar to an awake state. The cortex is active but the body is atonic (semi-paralysed) so we do not get up and act out our dreams. We generally need to be awake for several seconds in order to remember dreams.
What’s normal
Understanding normal sleep reduces the pressure of inaccurate sleep expectations.
We cycle through all the stages of sleep every 90 minutes (with a range of 70-100 minutes).
We start the night in very light sleep called NREM1. We generally spend around 5% of the night in transitional sleep, which can be described as half-awake/half-asleep.
Next is our dominant sleep NREM 2 or N2.
After about 25-30 minutes of sleep, we descend into Slow Wave Sleep (SWS), Deep Sleep or Delta Sleep, known as Non-Rapid Eye Movement 3 (NREM 3 or N3). Only 20% of the night is spent in Deep Sleep. Children secrete Growth Hormone (GH) during N3 while adults have reduced GH secretion to repair damaged cells.
SWS is followed by NREM 2 sleep and then we go into Rapid Eye Movement sleep (REM) – Dream Sleep. In REM sleep, we have rolling eye movements, hence the name.
A young healthy person may have 2-3 wakes a night but may not be aware of them. As we age, our sleep changes as does everything else. With increasing age, our sleep is characterised by an increase in the number of wakes. Very light sleep increases dramatically with age, and there is more rapid cycling between N1 & N2. Deep Sleep is reduced.
All of these changes are a normal part of the ageing process. It is so important to be active mentally and physically with increasing age. When older adults keep their fitness up, the prevalence of insomnia is the same as the general population. Exploring diet and exercise regimen and making relevant changes is another component of healthy sleep.
Improving sleep
It is useful to remember that we learn how not to sleep well therefore we can learn to sleep better again.
- Have a constant waking time as much as possible. This behaviour anchors sleep to the environment and sets a sleep/wake pattern for the brain. Going to bed at a certain time does not guarantee sleep onset unless you are feeling sleepy.
- Outside exercise and morning light is a great way to suppress your sleep hormone melatonin and to help you feel more alert – even 20 minutes is useful.
- Reduce exposure to bright light and electronic devices (blue/green light) at night make space for some much needed “slow down time.”
- Deal with the necessities and then figuratively put them into the background. Holding onto concerns, worries, plans will only keep you awake.
- If in bed and feeling wide awake and wired – don’t stay there, get up, have a gentle stretch, release those tight body muscles – breathe. You could sit on the edge of the bed in the dark and put the effort into staying awake. Sounds weird but it works, as trying too hard to sleep often sends a message to your brain there is danger. This strategy does the opposite. Sit up for 5-10 mins and then lie down and see what happens. You may need to repeat this strategy.
ED: Clinical Associate Professor Delwyn Bartlett is from The Woolcock Institute of Medical Research. For more information on sleep strategies or clinic services go to www.woolcock.org.au