Sleep and circadian rhythm
Sleep is proven to be one of the body’s most significant biological functions which affects physical performance, cognition, development and mental and physical health. It is governed by circadian rhythm which is basically a 24-hour internal clock running in the background of your brain and cycles between sleepiness and alertness at regular intervals. Not only is it controlled by hypothalamus but also external factors like lightness and darkness can impact it. When it’s dark at night, your eyes send a signal to the hypothalamus that it’s time to feel sleepy. Your brain, in turn, sends a signal to your body to release melatonin, which makes your body tired. That’s why your circadian rhythm tends to coincide with the cycle of daytime and night-time. It is recommended to go to bed and wake up day to day roughly at the same time to ensure the best sleep quality and keep the circadian clock in sync. In some cases, though, it can get disrupted and this can be seen in shift workers struggling to sleep well during the day or people suffering from jet lag. Experts say that most adults need between 7 and 9 hours of sleep every night. However, they also say that individual sleep needs vary, sometimes widely.
Sleep and athletic performance
From an athletic perspective, reductions in performance, decision- making ability, learning and cognition can occur alongside reductions in immune function and an increased susceptibility to weight gain. While there is limited research on exercise performance and sleep, a small number of studies have examined the effect of partial sleep deprivation on athletic performance in adults. Sadly, it has been reported that a range of psychomotor functions is negatively affected after only one night of restricted sleep. But good news is that muscle strength, lung power and endurance running are unaffected. Similar effects have been noticed in females following partial sleep deprivation, with gross motor functions being less affected by sleep loss than tasks requiring fast reaction times. From the available research, it appears that submaximal prolonged tasks may be more affected than maximal efforts, particularly after the first two nights of partial sleep deprivation.There are also a number of other biological functions that can be altered following sleep deprivation. Changes in glucose metabolism and neuroendocrine (cells that release hormones into the blood in response to stimulation of the nervous system) function as a result of chronic, partial sleep deprivation may result in alterations in carbohydrate metabolism, appetite, food intake, and protein synthesis. Ultimately, these factors may have a negative impact on an athlete’s nutritional, metabolic and endocrine status and as a result, potentially reduce athletic performance. This shows that we all need to get some adequate amount of beauty sleep not only to look well but also to fully enjoy active life on daily basis.
Power of napping
Active people suffering from some degree of sleep loss seem to benefit from napping. Some limited research has been done on sprint performance following partial sleep deprivation (4 h of sleep). Following a 30-min nap, 20-m sprint performance was increased (compared to no nap), alertness was increased, and sleepiness was decreased. In terms of cognitive performance, sleep supplementation in the form of napping has been shown to have a positive influence on cognitive tasks following a night of sleep deprivation (2 h). Naps can markedly reduce sleepiness and can be beneficial when learning skills, strategy or tactics. Napping may be beneficial for athletes who have to routinely wake early for training or competition and for athletes who are experiencing sleep deprivation. Personally, I can’t resist a good nap and find it really refreshing, especially after a long day at work or being out and about but still wanting to do some climbing or cycling. It is great to know that naps can pick us up but they shouldn’t be too long or too close to bedtime as then they can interfere with regular sleep pattern.
A few interesting sleep facts:
- Being sleep deprived means being as impaired as driving with a blood alcohol content of 0.8 which is illegal for drivers in many countries. This is one of the main reasons for car crashes.
- 12% people dream in back and white.
- Within 5 minutes of waking up, 50% of your dream is forgotten
- Ideally, falling asleep at night should take you 10-15 minutes
- Each child in a household increases the mother’s risk of getting insufficient sleep by 46%
- No vitamins, pills or drinks can replace good sleep. Consuming caffeine close to bedtime can affect your sleep. Alcohol and nicotine will also interfere with your sleep.
- Doing the same things every night before going to bed teaches your body that it’s time for bed. Try taking a bath or a shower, this will give you extra time in the morning.
Leeder, J., M. Glaister, K. Pizzoferro, J. Dawson, and C. Pedlar (2012). Sleep duration and quality in elite athletes measured using wristwatch actigraphy. J Sports Sci. 30:541- 545, https://www.tandfonline.com/doi/full/10.1080/02640414.2012.660188?scroll=top&needAccess=true. Accessed: June, 2019.
Reilly, T., and T. Deykin (1983). Effects of partial sleep loss on subjective states, psychomotor and physical performance tests. J. Hum. Move. Stud. 9:157-170, https://www.researchgate.net/publication/279564435_Effects_of_partial_sleep_loss_on_subjective_states_psychomotor_and_physical_performance_tests. Accessed: June, 2019.
Waterhouse, J., G. Atkinson, B. Edwards, and T. Reilly (2007). The role of a short post- lunch nap in improving cognitive, motor, and sprint performance in participants with partial sleep deprivation. J. Sports Sci. 25:1557-66, https://www.tandfonline.com/doi/full/10.1080/02640410701244983?scroll=top&needAccess=true. Accessed: June, 2019.