Why we Sleep? Review and Commentary.
When I were a lad, newly qualified and sporting the full length white coat (medical students wore shorties), sleep was quite a preoccupation. On my first ever weekend on-call, we clocked in of a Friday morning, and clocked off at 5pm the following Monday. In between times I had, I kid you not, a total of ten hours of fractured sleep, having personally admitted twenty-nine persons to the hospital. By the Monday I was way beyond tired – I had actually gone slightly mad. Only a spell in a major war could have prepared us.
I am so glad Matthew Walker’s book “Why We Sleep” wasn’t written in 1991. Bad enough to know that sleep deprivation had addled our ability to think and feel. How miserable it would have been to be informed by a Professor of Neuroscience at Berkeley, that deprivation was also a major risk factor for diabetes, heart disease, cancer, mental health problems and infertility. I’m actually surprised most of us are still alive.
Some physiology. Sleep is an example of a circadian rhythm. It is not principally governed by light, but by an intrinsic pacemaker sitting atop the optic chiasm. Only by the end of it, will the brain have adapted to the wrecking ball, which is a week of nights. Though at the time I was suspicious or dismissive, I now understand how it was, that in any cohort of junior docs, there was always one who went insane on nights. Caffeine to the rescue! An effective blocker of receptors for adenosine, our endogenous temazepam, it kids the brain into wakefulness with a half-life of six hours (so take care when you imbibe).
From the perspective of the sleeper, sleep is binary – either one is asleep, or one is awake. But science has taught us that in fact sleep has a highly differentiated neural architecture. Have you ever observed someone in REM sleep? It is pretty spooky. The sleeper is deeply asleep (REM sleepers are hardest to wake) but their eyes are doing an absolute fandango – zipping about in all directions. This contrasts with the quietude of NREM sleep which is, if anything, more weird, as it sees the whole brain pulse in self-generated synchrony.
With such a lot to memorise in your medical degree – have you studied how best to learn? A full night of sleep (around eight hours) will give you a 40% recall advantage over someone who has slept five hours or less. Sleep works by shifting memory from short term storage in the hippocampus to long term storage in the cortex. This feat of filing happens during NREM sleep – especially when associated with little explosions of neuronal activity called “sleep spindles”. Sleep spindles occur more towards the end of sleep – the bit of sleep we are most likely to sacrifice after a late night hitting the books or the bottle. Sadly, spindles have more or less packed in by the age of 50.
Unless you have an actual sleep disorder, as a student your deprivation is most likely self-inflicted. You either go to bed too late or get up too early to allow yourself the necessary eight. Walker quotes research on the impact on reaction times of different intensities of deprivation. Six hours per night for ten days (a duration some of us unwisely consider normal) had the same impact as one night of no sleep at all – a 400% worsening compared with the 8-hour brigade.
A common manifestation of deprivation is “microsleeps” – a second of slumber long enough to drift your car into an adjoining lane. I am ashamed to confess that in my twenties I frequently drove in a state of post on-call exhaustion – chasing a lassie who lived up the M5. I fought microsleeps with an open window, coffee and short naps in service areas. Once I was crawling along the North Circular after a 33 hour shift at Ealing Hospital (including, to be fair, a full four hours of fitful sleep) when I came to an abrupt halt – I’d only rammed into the rear bumper of a police car. It is not illegal to drive whilst exhausted (should it be?), but it is now illegal to make people work dangerously long hours – thanks to those meddling desk-jockeys in Brussels and their “European Working Time Directive”. A colleague called Dr Chris Johnstone won a High Court battle against his employer for making him work ridiculous hours as a junior obstetrician – he too had fallen asleep at the wheel.
So much for how Walker’s message impacts us personally as students and practitioners, but how should we engage with sleep in the clinic and on the ward? I was delighted to see UHBristol was running a campaign to make to the hospital quieter at night. Recovering from the effects of a motorbike crash in my late teens, I experienced the tyranny of two night-nurses who took sadistic pleasure in shouting and clanging their way through the wee small hours. Please, do what you can to preserve the delicate and healing sleep of in-patients in your vicinity. And in the clinic? In my surgery we practically never issue more than short (7-14d) courses of hypnotics. Why? Because they are habit-forming and side-effect inducing and typically lead to rebound insomnia. Most of all, they don’t create normal sleep. More confessions. About twice a year, I’ve been in the habit of taking 5mg (half a tab), of prescribed Temazepam, when I find myself wide awake in the middle of the night with a big event the following day. It works, it gets me to sleep. But all the evidence suggests that that drug-induced sleep is not equivalent to natural sleep. In particular, it lacks the normal, memory-enhancing, slow-wave, NREM sleep. Likely I get no net benefit from that slightly longer time nominally spent “asleep”.
This is a great book. I’d go so far as to say it is a must-read for medics. The style is a not world-class – at times a little messianic. But by the breadth of its scope, and the depth of its scientific foundations (including many of the author’s own studies) it serves to transform the reader’s appreciation of the genius and the jeopardy of sleep. Guys, we really have got some catch-up to do here, deepening our knowledge of the facts, valuing our own sleep, and learning how to include it in our clinical conversations. Really, sleep history should be part of every clerking consultation. This summer we run, for the first time, an SSC on sleep. Its title “Sleep: Chief Nourisher” borrows from those famous lines of Shakespeare. Just think, completely natural, free and profoundly effective. Go sleep (eight hours)!
I am so glad Matthew Walker’s book “Why We Sleep” wasn’t written in 1991. Bad enough to know that sleep deprivation had addled our ability to think and feel. How miserable it would have been to be informed by a Professor of Neuroscience at Berkeley, that deprivation was also a major risk factor for diabetes, heart disease, cancer, mental health problems and infertility. I’m actually surprised most of us are still alive.
Some physiology. Sleep is an example of a circadian rhythm. It is not principally governed by light, but by an intrinsic pacemaker sitting atop the optic chiasm. Only by the end of it, will the brain have adapted to the wrecking ball, which is a week of nights. Though at the time I was suspicious or dismissive, I now understand how it was, that in any cohort of junior docs, there was always one who went insane on nights. Caffeine to the rescue! An effective blocker of receptors for adenosine, our endogenous temazepam, it kids the brain into wakefulness with a half-life of six hours (so take care when you imbibe).
From the perspective of the sleeper, sleep is binary – either one is asleep, or one is awake. But science has taught us that in fact sleep has a highly differentiated neural architecture. Have you ever observed someone in REM sleep? It is pretty spooky. The sleeper is deeply asleep (REM sleepers are hardest to wake) but their eyes are doing an absolute fandango – zipping about in all directions. This contrasts with the quietude of NREM sleep which is, if anything, more weird, as it sees the whole brain pulse in self-generated synchrony.
With such a lot to memorise in your medical degree – have you studied how best to learn? A full night of sleep (around eight hours) will give you a 40% recall advantage over someone who has slept five hours or less. Sleep works by shifting memory from short term storage in the hippocampus to long term storage in the cortex. This feat of filing happens during NREM sleep – especially when associated with little explosions of neuronal activity called “sleep spindles”. Sleep spindles occur more towards the end of sleep – the bit of sleep we are most likely to sacrifice after a late night hitting the books or the bottle. Sadly, spindles have more or less packed in by the age of 50.
Unless you have an actual sleep disorder, as a student your deprivation is most likely self-inflicted. You either go to bed too late or get up too early to allow yourself the necessary eight. Walker quotes research on the impact on reaction times of different intensities of deprivation. Six hours per night for ten days (a duration some of us unwisely consider normal) had the same impact as one night of no sleep at all – a 400% worsening compared with the 8-hour brigade.
A common manifestation of deprivation is “microsleeps” – a second of slumber long enough to drift your car into an adjoining lane. I am ashamed to confess that in my twenties I frequently drove in a state of post on-call exhaustion – chasing a lassie who lived up the M5. I fought microsleeps with an open window, coffee and short naps in service areas. Once I was crawling along the North Circular after a 33 hour shift at Ealing Hospital (including, to be fair, a full four hours of fitful sleep) when I came to an abrupt halt – I’d only rammed into the rear bumper of a police car. It is not illegal to drive whilst exhausted (should it be?), but it is now illegal to make people work dangerously long hours – thanks to those meddling desk-jockeys in Brussels and their “European Working Time Directive”. A colleague called Dr Chris Johnstone won a High Court battle against his employer for making him work ridiculous hours as a junior obstetrician – he too had fallen asleep at the wheel.
So much for how Walker’s message impacts us personally as students and practitioners, but how should we engage with sleep in the clinic and on the ward? I was delighted to see UHBristol was running a campaign to make to the hospital quieter at night. Recovering from the effects of a motorbike crash in my late teens, I experienced the tyranny of two night-nurses who took sadistic pleasure in shouting and clanging their way through the wee small hours. Please, do what you can to preserve the delicate and healing sleep of in-patients in your vicinity. And in the clinic? In my surgery we practically never issue more than short (7-14d) courses of hypnotics. Why? Because they are habit-forming and side-effect inducing and typically lead to rebound insomnia. Most of all, they don’t create normal sleep. More confessions. About twice a year, I’ve been in the habit of taking 5mg (half a tab), of prescribed Temazepam, when I find myself wide awake in the middle of the night with a big event the following day. It works, it gets me to sleep. But all the evidence suggests that that drug-induced sleep is not equivalent to natural sleep. In particular, it lacks the normal, memory-enhancing, slow-wave, NREM sleep. Likely I get no net benefit from that slightly longer time nominally spent “asleep”.
This is a great book. I’d go so far as to say it is a must-read for medics. The style is a not world-class – at times a little messianic. But by the breadth of its scope, and the depth of its scientific foundations (including many of the author’s own studies) it serves to transform the reader’s appreciation of the genius and the jeopardy of sleep. Guys, we really have got some catch-up to do here, deepening our knowledge of the facts, valuing our own sleep, and learning how to include it in our clinical conversations. Really, sleep history should be part of every clerking consultation. This summer we run, for the first time, an SSC on sleep. Its title “Sleep: Chief Nourisher” borrows from those famous lines of Shakespeare. Just think, completely natural, free and profoundly effective. Go sleep (eight hours)!
Sleep that knits up the ravell’d sleave of care, the death of each day’s life, sore labour’s bath, balm of hurt minds, great nature’s second course, chief nourisher in life’s feast. [Macbeth Act 2, Scene 2].