Sleep could be the one factor preventing you from achieving your fitness, weight loss or training goals. Even professional athletes with the best training program could be kept off the podium for not getting their zzz鈥檚.
Why is sleep so important?
When we train in the gym, at the track, in a game or on the bike, we are damaging our muscles with minor micro tears, using glycogen and fat stores as well as stressing our entire system. But contrary to what most people think, we don鈥檛 get faster or stronger simply from training. Our results are dependent on how quickly we can repair and regenerate from our training. This regeneration only happens while we sleep, specifically during the Rapid Eye Movement (REM) phase of sleeping.听
There are five phases of sleeping. Each phase lasts for a certain amount of time allowing your body to fall deeper and deeper into unconsciousness. One full sleep cycle typically takes 90 minutes, so your body will continue to repeat the cycle for as many hours as you sleep. The REM sleep cycle isn鈥檛 until phase four so if your sleep quality is poor, you may never make it to the REM phase or the cycle may be interrupted, forcing your to start the cycle over from the beginning. Since most people only spend about 30 minutes in the REM phase, the length and the quality of your sleep determines how quickly you can regenerate and recover.
Why is the REM phase of sleep so important?听
All of the magic happens in this phase. One of our bodies鈥� most powerful hormones, the human growth hormone (HGH) is produced in the REM phase of sleep. The main function of HGH is to repair and regenerate but it also has several other beneficial functions such as: increasing calcium retention which helps maintain bone mass, promotes fat loss, reduces fat storage, supports your immune system, improves mental and cognitive functions and keeps your organs operating smoothly. That is a lot of work that needs be done in a very short period of time.
How does lack of sleep lead to obesity?
HGH isn鈥檛 the only hormone affected by sleep. During sleep, the body also balances two hunger-controlling hormones called ghrelin and leptin. A study in the journal PLoS Medicine showed a strong correlation between limited sleep and high levels of hunger-inducing ghrelin with low levels of the satisfaction inducing hormone, leptin. With hormones both making you hungry and not allowing you to feel satisfied you can understand why they have linked obesity with a lack of sleep.
Obesity has also been linked to high levels of cortisol. As we force our bodies to push through life on little sleep, it seeks out another energy source leading to an increase in the production of a hormone called cortisol. Cortisol works as a counter hormone to testosterone, human growth hormone and other muscle building hormones by breaking down your muscle tissue to release amino acids for energy.
Cortisol is very useful when it is released as a flight or fight response but today cortisol is also being released during tough training days or any high stress situation, either mental or physical. Add a lack of sleep with the reality of working a stressful job, taking care of the kids, going through a divorce or overtraining and it results in constant high levels of cortisol.
As an endurance athlete, you may be interested to know how sleep also affects your glycogen stores. Glycogen is the form of glucose that your body stores for your muscles to use as energy later and is the energy source that athletes rely on for the first hour of exercise. These stores are pretty easy to fill by eating carbohydrate rich foods. However, if you do not get a sufficient amount of sleep, your body will slow down how well you store glycogen. This means that during your next workout, you may run out of fuel halfway through which is not ideal, especially if you have a six hour ride ahead of you.
Most of us understand the benefits of exercise and good nutrition but the quality and number of hours we sleep is often overlooked. In our quest to get more done in a day, sleep is something that usually gets accounted for as wasted time. It is likely that if you miss your recommended eight hours once in a while you probably won鈥檛 even notice it. But most people make a habit of sleeping less to get more done. By sleeping only seven hours a night, just one hour less, by the end of the week you will have lost almost a full nights sleep! That is a lot of serious REM time that your body is missing.
If you think you can make up the time on the weekends by sleeping in until noon,听 studies show that it is most beneficial to get your full dose of sleep within the 24 hour period so as not to disrupt the normal circadian rhythm of your body and your hormones. For this reason, if you missed your full dose at night, a short 20-40 minute nap will help bring you back on track. However, napping for any longer than that and you might start to mess up the rhythm completely, throwing off your normal night time routine as well.
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