“Sleep is extremely important to me – I need to rest and recover in order for the training I do to be absorbed by my body” – Usain Bolt.
Almost all of us spend about a third of our lives asleep. Every night we prepare ourselves for this ritual, put on our pyjamas, lie down in our beds and, depending on our ability to achieve this state, we fall asleep. Almost every day of our lives finishes in this manner, and the next day only starts when we awake. Not only humans do this but also animals do the same thing, apart from putting on pyjamas. Though some animals, for example birds and aquatic mammals, sleep with only half of their brain at a time so that they can be aware of their surroundings and any dangers.
It is clearly an evolutionary development that is advantageous otherwise it would not be so widespread and would have disappeared a long time ago. But why do we sleep and what happens when we are sleeping?
First of all it is important to clarify that sleep is divided into various stages. The first division to note is that between REM (Rapid Eye Movement) sleep and NREM (Non REM). NREM sleep is further divided into 3 stages. The first stage is when you are preparing for sleep. Your eyes are closed but it is very easy to wake you. You may have involuntary muscle movements that are known as hypnic jerks. This phase lasts for about 10-15 minutes. Stage 2 is light sleep in which the heart rate slows and body temperature drops. Stage 3 is the deep sleep stage.
It's harder to rouse you during this stage, and if someone woke you up, you would feel disoriented for a few minutes. During this deep stage of NREM sleep, the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system. It is also the stage in which the Human Growth Hormone (HGH) is released. This is the final part of NREM sleep, after which comes the REM stage. During REM sleep the brain is flooded with chemical substances. You dream during the REM stage while the brain switches off the connection to the spinal cord so as to prevent you from “unwisely” enacting your dreams. If the connection is not switched off “REM sleep behaviour disorder” can lead to some occasionally humorous situations, but also to some extremely dangerous ones. Observing someone during the normal REM stage of sleep is almost like observing a dead person due to the absolute inactivity, except of course for breathing and heartbeat. This stage has been compared to the nightly back up of a computer system. The Hippocampus works to transfer recently learned information to the neo-cortex for later recall. This includes all kinds of information, from muscle movements to visual and written information. Everything significant that has happened to us during the day is processed by the brain, analysed and then archived in the correct place. It has been shown that when people are learning a new skill or ability a lack of REM sleep will hinder this process while sufficient quantities of REM sleep will assist the learning process.
It is important to note that the 4 stages of NREM 1, 2 and 3 plus REM do not occur once in a night but follow a pattern of cycles, normally 4 times, though there can be 5 cycles. Therefore once the first REM stage has been completed (normally quite short) we go back through the 3 stages and then return to REM sleep again. Each subsequent period of REM sleep being longer than the previous, as can be seen and evidenced in blue in the above diagram.. We are clearly doing more archive work! This means that sleeping through all 4 NREM/REM cycles before waking is important for our cognitive and mental welfare. At the same time most of the deep Stage 3 sleep in which bodily repairs are being made occurs in the first part of the night and this has a profound significance for athletes. Going to bed early and waking early will be good for our bodies but perhaps not so good for our minds or learning processes. Going to bed late but sleeping till late may be better for our minds but not so good for our bodies. Plus the fact of skimping on sleep may mean only being able to accomplish 3 cycles instead of the more normal 4. It is good practice for adults to get about 8 hours of undisturbed sleep every night. For athletes this is even more important because of the negative effects of insufficient sleep. Getting 9 to 10 hours sleep may be better.
But what are the negative effects that an athlete can expect to encounter if he is burning the candle at both ends. The most common at the physical level will concern slower recovery of muscle fatigue, lower stores of muscle glycogen, higher risks of injury and illness, a worsened glucose metabolism, poor stress regulation, hormonal imbalances and unwanted weight gain. From a mental and neuromuscular point of view we could see memory and learning difficulties, difficulties in motor function, slower reaction times, loss of focus and generally lower levels of motivation. There can be no doubt that all these factors will translate into worse performance both in training and competing.
What can we do as athletes to improve our chances of getting a good nights sleep?
First of all practice a good sleep hygiene. I don’t wish to suggest that any of us with a family, work and social life should adopt a monastic approach. We would probably soon find ourselves with more problems than a simple drop in our performance – companions, children, work colleagues and friends would not take long to point this out to us, and probably in no uncertain terms. However there are some things that we can do to improve our chances of a night of rest and rebuilding.
1. Go to bed at a regular time and maybe even adapt some before bed rituals. The human body and mind is happier and more relaxed with a regular schedule.
2. Avoid mind-stimulating activities for some time before bedtime. In particular smart phones, tablets and computers that emit a brain stimulating light should be avoided. The blue-light from electrical appliances acts as a suppressant of the sleep inducing hormone melatonin (more about that below). You can purchase blue-light blocking glasses if you really have to look at a digital screen in the evening.
3. Maintain the bedroom temperature between 15 – 19°C or 60 – 67°F. Since body temperature tends to diminish at the onset of sleep this temperature will assist in achieving this objective.
4. Evening exercise has been shown to inhibit sleep through the fact of raising body temperature. I know, I know sometimes you just have to train in the evenings. If you can, try to exercise in the morning, afternoon or early evening especially for harder or more intense sessions and in any case try to finish a few hours before bedtime.
Secondly, but probably less importantly, there are a number of nutritional substances that can help us.
1. The most obvious is Melatonin. It has long been known that our natural sources of the hormone melatonin regulate circadian rhythms. Dark stimulates our natural production of melatonin thereby signaling that it is time to sleep. Light on the other hand inhibits production and thereby signals that it is time to awake. Theoretically taking melatonin as a supplement a few hours before going to bed could help in sleeping. Research does not totally agree with this though some people find that it helps.
2. Consumption of protein in the evening has been shown to improve sleep. Even if it doesn’t improve your sleep it will still be helpful for protein synthesis and the promotion of muscle growth and repair.
3. Many people swear by the efficacy of a glass of warm milk and although research doesn’t back this up the placebo and feel good effect may actually go a long way. It also contains protein so a win-win.
4. Coffee? It depends how sensitive you are to caffeine. It is probably better to avoid it after mid afternoon.
5. Higher levels of vitamin D have been linked to decreased times of falling asleep. If you live in far northern latitudes (natural vitamin D production is dependent on sun exposure) it may be useful to look into your levels of this important vitamin. In any case low levels of vitamin D are linked to poor sport performance as well as other problems.
6. Magnesium deficiencies can lead to insomnia and so called “restless leg” syndrome. Magnesium helps maintain normal levels of blood pressure and blood sugar thereby promoting better relaxation and sleeping. Magnesium supplements are easily available but most nuts and seeds contain high levels of magnesium.
7. Some fruits such as tart cherries and kiwis have also been linked to faster falling asleep times, less sleep disturbance and greater total sleep time.
If you are cheating on sleeping you are almost certainly not fulfilling your athletic potential. Try out some of the above suggestions if you feel that sleep loss may be limiting you.