Sleep. Do you get enough? Probably not
Sleep was recently feted by the New York Times as a status symbol on the grounds that everyone wants it... And yet, despite this dearth, we still freebase on coffee and alcohol and blue light, doing little to increase our chances of getting any. It’s time we wised up. As director of Sleep Science at University of California, Berkeley, Matthew Walker, marvellously deliniates in his new book Why We Sleep, sleep is central to most aspects of our physical and mental wellbeing. And, in terms of hormones, it is absolutely vital.
What is the Circadian Rhythm?
From the Latin circa, ‘around’ and diem, ‘day’, circadian rhythm refers to the built in daily clock shared by all plants and animals.
So far, so simple. But it transpires this rhythm governs much more than just sleeping and waking. This year’s Nobel Prize in Medicine was given to three researchers who demonstrated how the Circadian Rhythm is hugely important in a great deal of our body’s processes, from changes in blood pressure to preparation of digestive enzymes to whether we will get Alzheimer’s to - you guessed it - the secretion of hormones which may or may not make you moody...
Tell me more.
Daylight is the primary regulator: when light starts to fade at dusk, the pineal gland (in the brain) releases the hormone melatonin and makes us drowsy.
“Melatonin plays other significant roles in the body,” says Lorna Driver-Davies, Clinical and Education Manager at Wild Nutrition. “One being the timing and release of female reproductive hormones such as oestrogen and progesterone which guide the onset, frequency and duration of menstrual cycles in women.
If patients come to see me with issues relating to PMS, irregular cycles or fertility, one of the first things I look at is their sleep hygiene.”
Light seems important.
It sure is. Light of any kind will disrupt our rhythm, but research shows that blue light - from laptops, phone screens, tablets and TV - has the most negative impact.
“Part of the lifestyle protocol I might look at with a client would be stopping any social media by 7.30pm, no Instagram etc,” continues Driver-Davies. “Historically, we might sit by a fire in the evening, but essentially dusk would mean dark. The evening should be about winding down.”
And in the morning?
Levels of melatonin drop at sunrise, and are replaced with cortisol, a stress hormone that will wake you up.
If you go to bed stressed, you will have raised cortisol levels - and therefore be muddling your hormone balance. A little evening meditation can make all the difference.
Alongside melatonin, what other hormones are produced while you sleep?
As ever, it’s complicated. In essence though, your whole delicate network of hormones is managed in relation to your circadian rhythm, and if that is off kilter it will have a chain effect on all hormonal activity.
What about the different stages of sleep?
Here, Walker’s book is especially fascinating. He delineates how a sleep cycle is 90 minutes. Each begins with NREM sleep (non-rapid eye movement) during which the brain weeds out un-necessary neural connections (eg memories we don’t need), then goes into and REM (rapid eye movement, or ‘dream’ sleep) which strengthens the remaining connections (sharpening us up for the next day). Emotional processing also happens during REM, taking the edge off painful memories and allowing the brain’s rational prefrontal cortex to regain control over emotional reactions - hence the relationship between REM, mood and even mental health.
And if you can’t get to sleep, or wake up in the night?
Walker recommends getting up and going into a different room. Read a book - no screens - or better yet, meditate. “Meditation quiets the mind, and dampens the ‘flight / fright’ branch of the nervous system which is a key feature of insomnia.”
I find sleeping pills can help..
“Unfortunately,” Walker continues, “ the current sleeping pills we have do not produce naturalistic sleep: they sedate, and sedation is very different from sleep, without its natural restorative benefits.”
Inadequate sleep will also decrease levels of satiety-signalling hormone, leptin, and increase levels of hunger-signalling hormone, ghrelin. Which is why when you’re tired it is exponentially harder to get through the day without grazing.
Further, after a bad night your levels of dopamine are likely to be low, so you will be reaching for a rush of sugar or caffeine to get you through - both lowering your chances for the next evening, and potentially contributing to sleep-related weight gain.