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Dancers and Sleep
(Posted 25/07/2018 by Admin)
(image copyright Jeremy Leslie-Spinks)
“Dancers have more bones than most people, and on the days when you work hard you are sure that you have somehow accumulated more bones than you started with.”
— Martha Graham
Dancing can be exhausting, and after a working day, you really need to sleep. Perfectly normal, but have you ever asked yourself what sleep actually is? What happens when you sleep — why do you need it?
You may know about “Circadian Rhythm”, the cycle of changes in your body over 24 hours, which govern your biological clock [1]. They’re based on strong external signals like daylight and darkness, or the timing of your work schedule, and they strongly influence your need to sleep at night and wake up in the morning. This shows in the varying levels of your “stress” hormone, cortisol. Normally, cortisol secretion kicks off when you wake at around 6 or 7 in the morning, climbs until around 9, tapers off until noon, and decreases throughout the afternoon, and even further when you sleep. Your “sleep” hormone, melatonin stays roughly constant during the day, decreasing as you go to sleep, and rising from about midnight until you wake up, when it falls again. A diagramme of your circadian rhythm across one day and night might look like this:
(image copyright: Jeremy Leslie-Spinks)
Another element here is “homeostasis”, the continuous regulation of your normal state – things like body warmth, blood pressure, chemical balances in your system and so on. To keep the homeostatic process going you use stored fuel, and this makes you tired; in fact, from your first awakening, there’s a slow build-up throughout the day of the need to sleep, becoming acute by late evening, until some people literally cannot stay awake any longer. Through the night, your sleep need slowly decreases, until you wake up. Your varying impulse to sleep across 24 hours could be shown on a diagramme like this:
(image copyright: Jeremy Leslie-Spinks)
The barrage of instructions from these two independent rhythms, telling you to nod off or else to wake up, can make sleeping quite tricky unless they are coordinated with each other (even more so for dancers, whose activity peak during evening performances directly conflicts with normal sleep-and-wake rhythms). This is why jet-lag is so disruptive. The daylight/darkness signals from your circadian rhythm, the work/function-based demands of the altered timetable, and the cumulative exhaustion of your homeostatic cycle all come into conflict. This plays havoc with your sleep patterns, and you may not be able to readjust for several days. It’s a problem often encountered while touring, and we’ll be looking at the life of a dancer on tour in a later post.
Sleep in itself doesn’t just mean not being awake [2]. It’s a whole series of processes, as important as breathing, digestion, hydration or exercise, with its own characteristics. It comes in two different phases, which are labelled by what you do with your eyes during sleep (apart from closing them…).
When you drift off, you first pass through various stages of “Non-Rapid Eye Movement” (NREM) sleep. In the process, the activity in your brain, cardiorespiratory and cardiovascular systems varies quite dramatically. The sleep phase where you dream the most, involves rapid movements of your closed eyes – the “Rapid Eye Movement” (REM) phase [3,6].
During the first NREM stage, you pass from wakefulness to the beginning of sleep. Your muscle activity and your brainwaves slow down. (EEG monitoring could track your brainwaves changing from their standard waking alpha frequency into the slower theta waves). Now is when you might feel a sensation of falling, followed by an involuntary “muscle jump” (myoclonic twitch).
In the second NREM stage, brain activity slows down even further and becomes irregular. Your brainwaves now will be slow, widely spaced peaks and troughs and corresponding muscle relaxation (K-complexes), alternating with sudden tight clusters of rapid activity and muscular tension (spindles).
The third and fourth NREM stages feature even slower, delta brainwaves, alternating with shallower, more rapid profiles. By now you’d be sleeping quite deeply. It would be hard to wake you up, and if that happened, you would be inefficient and confused for some time. (This is the time when children may have night terrors or start sleepwalking).
REM sleep, the next phase, is totally different. There’s a lot going on now – your brain activity is fast and out of synchronization, as though you were awake. You are now again in a theta brainwave frequency [2]. Your eyes move rapidly in all directions, your pulse speeds up, your muscles are sometimes temporarily paralysed, you may experience myoclonic twitch, and your blood pressure increases.
With all these different types of sleep, the most important thing for your health is enough of the right combination of sleep varieties. Your body needs seven or eight hours of real sleep, made up of alternating NREM and REM cycles through four to six repetitions per night. The sequence and timing of these components will change from one night to the next, and so, of course, will the activity in your body and your brain.
One part of all this which is important to us as dancers is that we learn and process movement and choreography best when Stage Two of NREM sleep happens late at night.
“Muses work all day long, then at night get together and dance…“.
— Edgar Degas
Doing without sufficient sleep may seem tempting if you want to use the time for travel, study, entertainment or social activity. Maybe you think you don’t really need it. Maybe there are more exciting or interesting things to do (stay up gaming, go out clubbing, hang out with friends), maybe you’re just not ready for bed – what difference does it make? It’s your body isn’t it? You reckon you know what you want – just because everyone else flops into bed all night doesn’t mean you have to do the same, does it?
Well actually, yes, it does mean precisely that. Dancers need sleep – without enough of it they soon won’t be dancers at all. Chronic Sleep Deprivation (CSD) produces significant physical and psychological effects.
Your brain will be affected, for one thing [4]. It processes the day’s new impressions and memories while you sleep [5]. At the same time, cerebrospinal fluid moves up into the brain via the glymphatic system, to flush away accumulated toxins and beta-amyloid protein (associated with the development of Alzheimer’s disease) from the spaces or interstices between brain cells. (Your brain actually contracts in volume by up to 60%, to open up these interstitial spaces and facilitate the cleaning process). Lack of sleep hinders these functions. Your ability to remember will be compromised, and you will increase your risk of developing dementia in later life.
Furthermore, as we all knew, lack of sleep really isn’t good for your looks. This may be caused by the associated high levels of adrenaline pushed out by your overactive nervous system. Neither adrenaline nor cortisol does your skin any favours. Excessive adrenaline also makes your heart work harder than necessary and sets you up for hyperlipidemia (high cholesterol). During normal sleep, your heart rate slows and your blood pressure falls. Without this “reset” mechanism, blood pressure remains constantly high, pretty much doubling your risk of a fatal heart attack or stroke.
Sleep deprivation also affects your sex life. It lowers your reproductive ability, causing testosterone levels to fall. During sleep, the hormones which are responsible for fertility (follicle-producing hormone and luteinizing hormone) are both produced. You mess with these at your peril, as your ability to reproduce is at stake here.
Your natural secretion of Human Growth Hormone (HGH) is vital to the growth and overnight repair of bone and muscle, using amino acids, the essential components of protein [8]. If your system is flooded with adrenaline and corticosteroids, HGH secretion is impeded, and these repairs cannot be carried out; this directly affects your ability to dance, as well as your options for recovering from injury.
And the list goes on. Shortage of sleep hinders your immune system, reducing your body’s defences against bowel cancer, prostate cancer and breast cancer. You’re also more likely to find yourself dealing with colds and infections, and your response to vaccinations will be reduced.
Insufficient sleep also disturbs your ghrelin-leptin balance. These are the hormones which control your appetite. If their relationship is pushed out of adjustment, your appetite will increase, leading to weight gain.
Liver function is also at risk — the vital jobs of detoxing, balancing blood sugar and processing adrenaline are all impaired by lack of sleep.
Bone health is yet another casualty of CSD [7]. Lack of sleep impacts directly on bone reformation, bone mineral density, bone thickness and the body’s ability to repair and maintain bone cells. For dancers, the implications are disturbing; we need strong, sturdy bones. Skeletal fragility can end your career.
On the psychological level, your concentration and mental acuity slide downhill as you get tired. After around 20 hours without sleep, you are impaired to the point where you could be considered too drunk to drive. You may well also be irritable, uncoordinated, lethargic and depressed. Does this sound like the dancer you want to be? Not really…
There is a helpful concept known as “sleep hygiene”, which only means the ritual aspect of the process (nothing to do with ironing your pyjamas or brushing your teeth). For sleep to be there when required, you need to set it up carefully. Try to go to bed and get up at about the same time every night. If your schedule allows it, eat a light meal, at least an hour or more before bedtime. It’s hard to sleep on a full stomach. Of course, if you’ve got a performance in the evening, this becomes much more difficult, but I hope class and rehearsals will start a little later next day, to give you time to catch up.
Then there’s your back. Dancers’ spines deal with all kinds of loading. Landing from jumps, lifting, acrobatic work, carrying weights, even normal movement patterns, everything presses downwards onto the strong, shock-absorbing intervertebral disks which cushion the 33 bones of your spinal column. This constant pressure has a cumulative effect; this evening, you may be as much as 2-3 centimetres shorter than you were this morning. During sleep, your spine is relieved of the vertical gravity load, so your intervertebral disks, free of the pressure of body-weight, can resume their normal shape and size. When you get up, you need to give your back enough time to stabilise itself in the new configuration, because you are taller this morning than you were last night. Try to avoid sudden, asymmetrical movements or loads, until you have “set” in a safe and normal state. (This might take up to half an hour).
Sleep posture is also important, especially for dancers. If you lie flat on your back, your spine will be lined up, as closely as possible to your normal standing alignment. Your pillow should let your neck lie in a normal, straight position. If the pillow is too low, your head drops backwards, exaggerating the curve of your neck – if it’s too high, you wind up trying to sleep with your chin tucked in. Both positions can affect your breathing, disturb your rest, and give you a sore neck in the morning. Obviously, your mattress needs to be soft enough and firm enough at the same time to support your back, even when lying on your side. (Some researchers [9] suggest that this position allows the most efficient functioning of the glymphatic process). A mattress which is too hard or too soft will not support you adequately, and may alter your spinal alignment, leading to discomfort and back pain. The worst position in which to sleep would be lying on your stomach, with your head twisted to one side so as to breathe. Spending the night like this strains your neck, shoulders, knees, ankles and toes and puts pressure on your internal organs. There must be an easier way…
For a couple of hours before you go to bed, try to wind down. Dim or extinguish a light here and there, turn down the music, reduce agitation and clamour. Your body will be starting to experience reduced levels of cortisol, and the melatonin will begin to kick in. Blue light, of the kind emitted by the screens of devices, is hard on melatonin, so try not to do too much television for the last hour or so. Leave all your electronics and small-screen devices turned off when you sleep, ideally not in your bedroom. The room needs to be as dark as you can get it, not too warm, and very quiet. If there has to be a nightlight, choose a warm colour — orange or red, and at low intensity. Light, noise and stress can all keep you awake. Also, alcohol doesn’t actually help. It may make you drowsy for a while, but you’ll wake up at about 3 in the morning, possibly very agitated, with a pounding heart and loads of stress, which will take a long time to calm down. Try to put all the incredibly exciting things that happened today out of your mind for the moment – you don’t want to spend the night replaying the video in your head.
If for some reason you really cannot sleep, don’t force yourself. Get out of bed, sit quietly somewhere (more chamomile tea, perhaps?) and go back to bed when you feel sleep coming on again. Maybe you can read yourself to sleep, or make a cup of hot milk, or some such thing. (Not coffee, and you have to know that black tea also contains quite a lot of caffeine).
Sometime, sooner or later (because you need to) you will get back to sleep… Tomorrow will be here any minute… Sleep tight….
“To realize our dream we must decide to wake up“.
— Josephine Baker
© Jeremy Leslie-Spinks
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