Sleep Yourself Fit
Quite simply sleep is a critical component of training. You're body gets fitter and adapts to training when you rest and sleep is the most powerful recovery weapon you have. Elite athletes are focusing more and more on sleep patterns in order to maximise their training benefit but why is sleep so critical?
* Growth Hormone: Your body releases Human Growth Hormone (HGH) in the deep sleep phase of your sleep cycles (see below for more) and increases cell devision and regeneration, in fact up to 75% of the growth hormone your body releases is thought to happen when you sleep. HGH is what you need to heal and repair damaged muscle fibres and tissues from those hard sessions...basically getting fitter!
* Mental effects & stress: Mental alterness, reaction times and your ability to manage emotions and stress are all affected by sleep - feeling sharp and ready to train and race is likely to be improved with more sleep.
* Injury Prevention: Though a combination of hormone release and improved mental function a recent study (Von Rossen et al, 2016) showed that amongst a group of elite athletes those getting over 8 hours sleep a night showed a massive 61% reduction in injury risk with another study (Le Meur et al, 2013) showing athletes getting less than 8 hour sleep a night had 1.7 times greater risk of injury.
* Kidney Function: Poor sleep has been linked to inhibited glucose metabolisation & insulin release resembling type 2 diabetes and hypoglycaemia. It is at night when your kidneys also work to rebalance water and electrolytes - vital for athletes.
* Immune Function: An increase in pro-inflammatory cytokines occurs after sleep loss and this is thought to contribute to increase immune system dysfunction - potentially increasing your likelihood of infections.
Sleep Cycles & Stages: You may have heard about 'sleep cycles' or 'phases' of sleep. The cycles and patterns of our sleep is actually quite a complicated area but in very basic terms as we sleep we move through a series of sleep cycles lasting roughly 90 minutes and within each cycle we move through a series of 5 stages:
NREM (Non Rapid Eye Movement) 1: Light sleep, where we drift in and out of sleep easily, some people will feel muscle contractions and a falling feeling as gradually your eye movements and muscle contractions start to slow.
NREM2: In this phase your heart rate will start to slow and your eye movement will cease. Generally body temperature will also drop and brainwaves are slowed.
NREM3: This phase is typically a transfer from a lighter sleep to a deep sleep, with slow 'delta' brain waves interspersed with shorter more rapid brain waves.
NREM4: This is your deep sleep where rapid brain waves are much less frequent, this is the phase of sleep that will leave you feeling confused and disoriented if woken from.
REM: Rapid Eye Movement is characterised by more rapid brain activity that mimics a waking state but whilst still asleep and is when you will often experience more intense or vivid dreams.
After about 90 minutes your will move back to stage 1 for a new cycle, as the night progresses so you move through a series of cycles but the time spent in each stage will change, with the latter stages of sleep characterised by less time spent in deep sleep and more in REM sleep. The important thing to recognise is that it is during your deep sleep (NREM 3 & 4) that growth hormone is released and that your immune system undergoes most beneficial changes. Interrupted sleep (as characterised by the images from my sleep profile last night) represent a big problem because each time you wake to interrupt a cycle you go back to the start reducing or even limiting time spent in the most beneficial (in recovery terms) stages.
Qaulity as well as Quantity: We commonly hear about a magical '8 hours' of sleep being the measure of a 'good night's sleep'. Certainly we would encourage athletes to be aiming for 7-9 hours sleep a night but it's not quite as simple as that. The qaulity of your sleep really of even more importance because of the need to move through the sleep cycles I have outlined above. Why is it that some nights you can get 7 hours of sleep, and some 9, but you feel better after the 7 hour sleep? The answer is the continuity. Check out the three sleep profiles below tracked using my Polar M430 on consecutive nights this week;
Whilst the first night I was actually in bed for longer my sleep was much more fragmented with interrupted sleep cycles and I ended up adapting my training the next day to a lighter session. The next day I went to bed at the same time, got up earlier but felt much more rested due tot he reduction in movement and generally having a more continuous movement through sleep cycles (movements can be seen as the yellow lines on the graphs. The 3rd night was better yet again, despite getting to bed nearly an hour later.
Sleep Hygiene: What can you do to improve your sleep and get fitter and stronger as a result? Well the answer really is about observing what we call good 'sleep hygiene'. Here are a few key tips to get you going;
* Avoid light and radiation from screens: A recent study (Figeurio et al) showed that exposure light form electronic displays reduced melatonin by up to 22%. Melatonin is critical to your sleep and wake functions. Banish smart phones and tablets from the bedroom and aim, as much as possible to give yourself a 90 minute window pre-bed clear of these devices.
* Develop a pattern: Aiming as much as possible to develop a routine and pattern of both behaviours (i.e. when do you brush your teeth, when do you dim the lights) and time you get into bed can massively help get your body back into a more natural and regular sync of sleeping and waking.
* Avoid stimulants: Avoid caffeine and alcohol late at night - both are sure fire ways of affecting both your ability to get to sleep and your ability to sleep uninterrupted. This is both through their ability to stimulate brain activity but also because of their diuretic effects.
* Food and drink: Eating your last meal a good 2 hours (ideally more) before bed is really important to ensure that your body is not still actively trying to digest a big meal as you get into bed, and whilst its important for all athletes to be hydrated try to avoid drinking to excess in the evenings - getting up to go to the toilet is a sure fire way if interrupting your sleep cycles! Some people, if they train or work late, might benefit from eating their main meal at lunchtime, with a lighter evening meal.
* Relax! It's obvious but most of us hope to relax, rather than continuously doing anything about it. Again this is about routines, perhaps for you it's a bath, or a short period of reading before you get into bed, for some it might even be meditation. Dim your lights and create a calm relaxing environment away from stress and distractions of smartphones or TVs.
* Environmental factors: A good mattress can be one of the most wise purchases any athlete can make. The decision is very personal but your mattress is one of the biggest factors in how well you sleep. Think about keeping your bedroom cool and investing in a blackout blind to limit light pollution, particularly if you are in a town or city. Ear plugs can be useful if you live in a noisy area.
* Control your stress: If you have a lot on your mind try to write down a list 'to do' tomorrow, clear these now from your mind before you go into your relaxing routine before bed, thinking over and over about work, family or money worries (or even training or racing stresses) really wont help. Controlled breathing techniques (such as tri-breathing where you breathe in for a count of 3, hold for a count of 3 and breath out for a count of 3) if you are very stressed can also help you start to calm down, and transition towards sleep. One of the really damaging effects of lack of sleep is that it also affects your ability to control stress...so a vicious cycle occurs where stress increases, affects your sleep, which in turn affects your stress. Seek further support if you do have chronic stress issues.
* Training times: Whilst exercise in general terms appears to have a beneficial effect on your ability to sleep because harder training sessions can elevate cortisol and leave a sustained increase in heart rate it is probably wise, where possible to avoid harder sessions in the final 2-3 hours before bed.
Track Yourself: When I ask athletes how they slept they often need to rely both on a good (or poor!) memory about an aspect of life that they often don't give a great deal of conscious thought to ('when did I actually get to bed??' for example) or on a sense of feeling or perception of quality of sleep which we are often not great at judging. Most commonly the response I get is a vague guess at the number of hours, and nothing about actual sleep quality.
As with all other aspects of training it's hard to measure progression without data and a benchmark. I strongly recommend athletes look to track their sleep using a watch. The Polar M430 for example uses a 3D accelerometer to measure when you fell asleep, your sleep continuity (quality), when you work and your overall sleeping time. By using a sleep tracker athletes can monitor sleep behaviours, see themes in sleeping patterns and link them to non sleep lifestyles and behaviours as well as track improvements and changes.
Le Meur et al, 2013. In Recovery for Performance in Sport. Human Kinetics. 2013
Von Rossen et al, 2016. Multiple Factors Explain Injury Risk in Adolescent Elite Athletes. Sc and J Med Sci Sports. Feb 16