First sleep studies Burger invented EEG (1924) which gave us the knowledge that brain waves change during the night.
However it wasn’t until the 50’s that Chicago University’s Eugene Aserinsky used this information to discover REM (Rapid Eye Movement) sleep (the deepest sleep and arguably the most refreshing you can have) when he applied this knowledge to sleep research. Just as I have discussed in this blog, Ultradian Rhythms can be observed to divide our day into convenient 90 minute cycles (and the reason why Yoga class is just that length), so our night is divided into periods of around 90 minutes in three different cycles of sleep depth and for most people this also normally includes waking up briefly 2 or 3 times.
Michael Mosley has summarised here (and details in his highly recommended book “Fast Asleep”) that there are two light stages of sleep, the first of which is so light that you are very easily woken from it, the second of which is accompanied by drops in both temperature and pulse rate as well as breathing rate of course. This is also the stage in which you experience that lashing out jump (a sign of stress according to Mosley) or at the very least an annoying jerky dance. The third (slow brain wave) deeper stage of sleep comes within an hour of nodding off. At this point you are very relaxed and difficult to rouse and your body is repairing itself, with a boost to the pituitary gland (the growth and repair hormone) and a wonderful boost to your immune system. So having more experience of this brainwave has an inevitable consequence of protecting you against colds, flu and COVID-19 – so worth an experiment of following our advice in Yoga Class this week about how to get more of the right kind of brain wave sleep. You can also check out this article if you want more of the science behind how this works. This is the time of night in which the CSF (cerebrospinal fluid) is increased and effectively washes away the toxins in your brain. A consequence of ageing can be the lessening of this type of sleep and therefore a lessoning of the detoxification which is vital to our mental health. You can immediately see the very clear link between this an Alzheimer’s disease and the memory loss we associate with the ageing process (not an inevitable part of ageing as we discover every week in Gentle Somatic Yoga Class).
The good news is that getting more of this deep sleep is within your control to a degree. You simply need to get to bed before midnight so that you increase your chances of getting to this life enhancing detoxifying brainwave in the early part of the night. Sticking to a very strict Sleep Hygiene Ritual is key if you want to improve your chances of avoiding dementia, and holding on to your memories. The essential elements of sleep hygeine will be part of our discussions in Gentle Somatic Yoga Class including debunking some taken-for-granted myths such as the ability of the blue light from your iPad keeping you awake.
Finally the eye flickering stage in which you dream your deepest dreams is also very important for organising your memory as well as helping to solve and process our bad memories and adrenalin inducing experiences whilst the corisol producing system is switched off. So you replay upsetting experiences whilst you are calm – a bit like being hypnotised and this helps you to “get over them”. You may even remember dreaming about one of your fears and know that for some reason you aren’t scared at all and after this you may experience less fear of this situation in your waking life. It is also the reason why you might wake up with a new view on an old problem so it’s best to leave your rumination in the late evening in a notebook by the bed and see what the night offers by way of processing them creatively.
At this stage, instead of jumping around like the second stage of sleep, your muscles are actually paralysed apart from the mad flicking of the eyes, which may be a sign that you are following the action of your film-like dream sequence (though we don’t know this for sure).