Sleep is a physiological state of relaxation of our mind and body, when our consciousness changes and we are less aware of our surroundings. During sleep, there are two basic phases that recur periodically - REM (rapid eye movement) sleep and non-REM sleep. The exact mechanisms and functions of sleep are not yet fully understood, but in general we can say with high confidence that sleep is essential for the regeneration of our bodies.
During sleep, we enter an anabolic state and most of our systems recover their capacities - e.g. immune, nervous, cardiovascular, musculoskeletal systems, and the body also gets rid of accumulated metabolic wastes. We spend approximately one-third of our lives sleeping. However, sleep is not the prerogative of humans alone, but can be found in some form in virtually all animals from insects to fish, from the smallest carrion fish to the longest sharks, which speaks volumes about its immense importance.
As I mentioned above, sleep can have a huge impact on our bodies, and a lack of it, known as sleep deprivation, can lead to many health problems. It is therefore ironic that some world figures often recommend sleeping less and preferring to engage in self-development or training, however, what effect can sleep deprivation have on our body composition?
The huge impact of sleep on changing body composition is demonstrated by the results of a recent study. In this RCT study with 23 participants included in the final analysis, the participants were divided into two groups. Both groups underwent strength training twice a week for ten weeks, but the other group was educated on how to improve the quality and quantity of their sleep. At the end of the study, both groups experienced comparable increases in fat-free tissue - 1.3 kg vs. 1.7 kg for the group that was educated on sleep hygiene techniques. However, the study found a huge difference in body fat changes in the two groups - while the first group gained 0.8 kg of adipose tissue, the second sleep-optimized group lost 1.8 kg of fat!
These effects of sleep in the context of changes in body composition are confirmed by other studies on this topic. For example, in a high-quality 2010 study with ten overweight participants, a weight loss of 3 kg in 14 days occurred during a weight reduction regimen. However, the composition of this weight loss varied greatly depending on the length of sleep. In fact, when the participants in this study were sleep deprived and slept only 5.5 hours per day, they lost only 20% of their adipose tissue and the remaining 80% came from fat-free body mass (mainly muscle and water)!
Conversely, if sufficient sleep of 8.5 hours was provided, most of the muscle mass was spared in the reduction - the weight loss then consisted of approximately 50% fat and 50% fat-free body mass. Scientists have explained these differences by the fact that sleep deprivation leads to hormonal changes and a greater sense of hunger (due to increased ghrelin levels, among other things). Most of us have certainly experienced this at some point and, if we are sleep deprived at night, have experienced a higher appetite the next day.
These studies clearly show that sleep is a very important factor that can determine the success of a weight loss diet or even a training program. A lot of athletes and everyday people make the mistake of focusing too much on other factors such as the right diet, the right training program, but very often forget about sleep, which can limit their results. Of course, I don't mean to say that other factors don't matter, but we can only really achieve maximum results if we have optimized all the factors (including sleep), which will then synergistically support each other.
Tips for better sleep
This brings us to sleep hygiene and practical recommendations on how to optimize the quality and quantity of our sleep, which can ultimately help us in the context of weight loss or body composition change, but also in many other areas of our lives.
1) OPTIMAL SLEEP DURATION
Like most nutrition recommendations, optimal sleep duration should be personalized to each individual, which is not the same for everyone, as it depends on genetic factors, environment, stress level or amount of training, and of course age, among other things. However, at the population level, there are very well-scientific recommendations set by the National Sleep Foundation (NSF) based on the scientific literature and other official sleep research organizations. It is also interesting to note that athletes, compared to the general population, seem to have a higher need for sleep.
2) ROUTINE
In terms of quality sleep, forming long-term habits that we follow every day can help. Ideally, we should go to bed and wake up at similar times, as irregularity can have a negative effect in terms of our circadian rhythms. It also turns out that each of us has a slightly different time of falling asleep and waking up - in fact, there are so-called chronotypes in the population that reflect individual preferences in terms of genetic make-up, and we can very roughly divide the population into 'night owls' and 'morning larks'.
3) PREPARING FOR SLEEP
We should not go to bed hungry or overfed. It's good to re-establish habits to follow before going to sleep. For some people, a hot bath before bed or meditation can help them relax.
4) REGULAR EXERCISE
Regular exercise can also help with sleep, and it doesn't have to be the gym or running, but sometimes just a longer walk and being out in the fresh air is enough. We usually sleep best when we are reasonably physically exhausted. Just beware of high-intensity workouts later in the evening, which can be rather disruptive to some people's sleep.
5) SUITABLE ENVIRONMENT
Before we go to bed, we should make sure we have a suitable environment where we can fall asleep comfortably. The bedroom should be neither too hot nor too cold. Around 18.3°C is recommended as the optimum temperature for adults to sleep. This slightly lower temperature helps to ensure an optimal body temperature, which is also slightly lower during sleep than during the day, and undisturbed sleep throughout the night. One study has even found that temperature is one of the most important factors for quality sleep. We should also make sure there is no unpleasant noise in the room. On the other hand, a soundscape - such as nature sounds or a soft melody - can help some people fall asleep. The room should also be sufficiently dark to avoid light smog, but in the morning it is a good idea to let the first rays of the sun wake you up naturally at sunrise.
6) COMFORT
Don't underestimate the choice of a quality mattress, duvet and pillows. All these little things can also affect the quality of your sleep. If we don't have suitable conditions in our bedroom, we can help ourselves by buying a new mattress, a fan in the hot summer months, a sleep mask or earplugs, for example.
7) BLUE LIGHT AND ELECTRONICS
One of the other possible causes of some sleep disorders may be blue light, which generally has stimulating effects - during the day it promotes alertness, reaction speed and mood, but at night these effects are not appropriate as it can disrupt circadian rhythms. In fact, light, especially light with a wavelength of 400-525 nm, which corresponds to blue light, blocks the production of melatonin and thus negatively affects sleep. Some studies have found higher rates of cancer, diabetes, cardiovascular disease and obesity in people working night shifts with high blue light exposure.
Therefore, avoid electronic devices that produce blue light (televisions, cell phones, tablets, computers, etc.) for 2-3 hours before bedtime and dim home lights. Replace electronic devices with a book, for example, and prefer warmer colours of lighting at night (red is the colour least likely to suppress natural melatonin production). If you still have to work at night, install apps on your electronic devices that optimally change the colour spectrum of the screen (suppress blue light) or wear special glasses with blue light filters.
8) SLEEP AFTER LUNCH (NAP)
A popular technique among athletes and the general public is a short revitalising sleep after lunch, known as a nap. This habit is even closely linked to some cultures and nations - some form of short nap after lunch or in the early afternoon can be found in Spain (siesta), Greece, Mexico or China.
It turns out that sleep after lunch, if set up correctly, can have many benefits, even in the context of improving physical performance. Although the evidence is still relatively scarce, some studies have indeed shown improved performance with regular practice of short naps after lunch.15
Even in this case, however, we should follow a few simple rules. Ideally, we should take advantage of the body's natural lull for a nap, which for most people occurs sometime between 1 pm and 3 pm. Sleep time is also important, as a long nap after lunch could disrupt our night's sleep or negatively affect our bedtime. Therefore, we should only sleep for about 20-30 minutes after lunch.
Literature
1) LEGER, D., et al. An international survey of sleeping problems in the general population. Current medical research and opinion, 2008, 24.1: 307-317.2.
2) JÅBEKK, Pål, et al. A randomized controlled pilot trial of sleep health education on body composition changes following 10 weeks resistance exercise. The Journal of Sports Medicine and Physical Fitness, 2020.
3) NEDELTCHEVA, Arlet V., et al. Insufficient sleep undermines dietary efforts to reduce adiposity. Annals of internal medicine, 2010, 153.7: 435-441.
4) CHAPUT, Jean-Philippe; DUTIL, Caroline; SAMPASA-KANYINGA, Hugues. Sleeping hours: what is the ideal number and how does age impact this?. Nature and science of sleep, 2018, 10: 421.
5) SIMPSON, N. S.; GIBBS, E. L.; MATHESON, G. O. Optimizing sleep to maximize performance: implications and recommendations for elite athletes. Scandinavian journal of medicine & science in sports, 2017, 27.3: 266-274.
6) LYDON, David M., et al. The within-person association between alcohol use and sleep duration and quality in situ: An experience sampling study. Addictive behaviors, 2016, 61: 68-73.
7) HATORI, Megumi, et al. Global rise of potential health hazards caused by blue light-induced circadian disruption in modern aging societies. npj Aging and Mechanisms of Disease, 2017, 3.1: 1-3.
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