SLEEP: the keeper of mystery

At least once in every 24 hours, we voluntarily and temporarily lose consciousness into a state of sleep. It's so normal we forget how remarkable this is.

It’s a strange experience to begin each day with a certain knowing that I have either had a good sleep or a not so good one. If it wasn’t for the apparent absence of everything I call me, myself and I each night during deep sleep, it might be possible to explore an experience that happens with-out me in more conscious ways. As it is, I wake up with no recollection of the actual experience of deep sleep although I am able to track to a certain extent the process of falling into sleep, and the process of surfacing from sleep and sometimes, of course, I remember odd fragments of dreaming. I think you would agree that most of the time between waking and sleeping is a vast unknown.

The yogic traditions (and other ancient wisdom practices) have clues for us to follow and one of these is the practice of yoganidrā or “yogic sleep” (more on this in the Companion Notes). It is typically offered as a form of guided relaxation where attention and experience is directed to the transitional state between waking and sleeping, called the hypnogogic state. In fact, it’s actually quite difficult to break the habit of a lifetime and hover in this state and not find ourselves either dipping in and out of full sleep or completely dropping off, which is an interesting idiom!

Yoganidrā proper is not an easy practice, in fact medieval yoga texts* describe the practice as synonymous to the profound meditative state of samādhi - so not really relaxation in the way we might crave it in modern terms as an antidote to the stresses of daily life, rather a relaxation that stills the body and the mind in order to experience a reality beyond that of the senses.

By the way, if you have come across something called Non-Sleep Deep Rest (NSDR) you will have landed on a more secular and contemporary label for the practice of yoganidrā.

*I’ll elaborate a little on textual references in the Companion Notes in case you want to pick up that thread.

1. THE SCIENCE OF SLEEP

It’s helpful to dip into a little bit of neuroscience here to understand something of what is going on in our brains when sleep is the mode of being.

Our exposure to diminishing daylight is the principal signal for the brain to begin organising its own daily reset, and the mechanism that does that is tiny, only about 1mm³ so about the size of a sesame seed. It’s called the suprachiasmatic nucleus and it sits at the crossover point of the optical nerves - take a look at the images below to map this information for yourself. At the onset of darkness, it instructs the pineal gland (another very small structure of about 5mm, so indeed about the size of a pine nut) to secrete a messenger hormone called melatonin and the message it circulates for the body systems is that it’s "time for bed”.

Having said that, melatonin doesn’t generate sleep rather it sets up the conditions for sleep and supports those conditions through the night, gradually dwindling towards the dawn. And, when daylight is perceived by the brain, seeping little by little through our closed eyelids, the suprachiasmatic nucelus ceases talking to the pineal gland and melatonin production stops - thereafter we and our body systems begin to waken.

This is the basis of our daily circadian rhythm and the first factor that influences our waking and sleep states.

Locating: Eye/Optic Nerve, Suprachiasmatic Nucleus, Pineal Gland

2. LARKS & OWLS

Everyone has a circadian rhythm of approximately 24 hours. It is our personal cycle of wakefulness and sleep that underlies other biological rhythms like the feeling of hunger or the need to go to the loo, or the up and down swings of our moods, and like a virtual assistant it keeps our daily hormonal calendar up to date. You will recognise your own rhythm when you pay attention to it, noticing when you feel uplifted, focused and ready to do things and when you feel more sloth-like, vague and distracted.

About 40% of adults veer towards the label of being “a morning person”, up with the larks, early to bed and early to rise. Then there are 30% who are definitely “not a morning person”, the night owls who are late to bed and late to rise. And, of course there are the in-betweeners. These rhythms are an evolutionary survival strategy and appear to be a genetic disposition although there is some research that indicates a certain melatonin disruption may be present in non-neurotypical folx that leads to greater differentiation in signature sleep patterns. (I’ll make sure I dig out the data in the Companion Notes).

3. SLEEP PRESSURE

The second factor that influences our wakeful and sleep cycles is a neurotransmitter called adenosine. This chemical collects progressively in the brain throughout the waking hours and the more of it there is, the more tired you will feel. It becomes a sort of heavy reminder that you have to put down the busyness of the day and actually get ready for bed and sleep.

The build up of adenosine starts to quieten the more wakeful parts of your brain, whilst at the same time stimulates the sleep inducing parts. It adjusts this balance until staying awake is no longer an option and sleep cannot be resisted; it usually tips the balance after 12-16 hours of being awake. Know the feeling?

You can of course wage a battle with adenosine if you have to or need to by drinking caffeine which muscles its way onto the adenosine receptors blocking the sleep pressure process. By the way, it’s worth remembering that caffeine has a ‘shelf life’ of between 5 and 7 hours before the brain is cleansed of it, so maybe that after dinner espresso is never such a great idea.

4. WAKE-SLEEP BALANCE

Wherever you are in the world as you read this your culture, like mine, likely demands a so-called Work-Life balance that is heavily weighted towards work and productivity. It is the nature of “late-stage capitalism” for many of us to feel that we have less and less agency over how we use our precious time. We might need side-hustles, a second or even third job, passive income streams, or longer shifts with fewer breaks (and breaks that are not remunerated), as well as the prospect of needing to work into the retirement years to manage even a relatively simple life-style.

Essentially, working life fills more of our waking life which adversely affects the underlying Wake-Sleep Balance that is managed by our circadian rhythm to the point that, we might be existing in a Work-Sleep cycle - not good. If we can begin to prioritise tending to our sleep habits in a more conscious way we might find that we can rebalance our waking hours between the working and not-working that is going to be hugely beneficial to our overall well-being.

5. AND WHAT ABOUT THE MYSTERY?

Well, the mystery remains a mystery in that without even a remnant of a conscious self in deep sleep it would seem that there is ‘nobody’ there to remember the experience. However, there does appear to be something like a subliminal state of awareness since, as I mentioned earlier, I am able to recall that I have been asleep and able to infer that it might have been a good sleep or a not-so-good sleep. Weirdly, it seems I am able to recall a sense of the absence of my everyday, autobiographical self.

Neuroscience and the ancient philosophies of India take different views on this: the former considers all our waking experiences to be the basis for consciousness which disappears in our deep sleep, while the latter considers deep sleep as the ground substance out of which consciousness, including the everyday self, arises. I’ll unpack this a bit more in the Companion Notes. Whatever the case, it’s clear that you and I embody daily something of the mystery of being alive in our circadian rhythm and that this mystery is as vital to life as our breath is.

That’s it for now! Did you see I made an audio version of this issue of Field Notes From The Body? Let me know if you’d like me to continue.

Sweet dreams,

Beverley

PS: If you are paid subscriber, then Companion Notes will be with you in a few days when I will follow up with more information on the brain in sleep and meditation, some guided practices, stories from the Greek myths (because I just can’t resist them) and I’ll share my favourite method for finding sleep when my brain is just too busy to settle by itself.

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