When you set a fitness or nutrition goal, you make adjustments to your diet and exercise, but what about your sleep? Sleep is one of the most often overlooked aspects of health and fitness and it is often the first to be compromised when trying to fit everything into a busy schedule.
According to the CDC, 35% of adults do not get the recommended 7+ hours of sleep per night.
Moderate sleep deprivation, such as chronically sleeping <7 hours per night, can have small impacts on your decisions and behaviors throughout the day and on your body’s regulation of physiological processes. Over time, these small impacts can create imbalances in your body’s ability to take in, store, and utilize energy. This causes those who have a shorter duration of nightly rest to have an increased risk for developing obesity, type 2 diabetes, hypertension, and cardiovascular disease.1
We all know that most people like to be awake during the day and get tired at night. This is more than just a preference; our brains operate according to the circadian rhythm – a 24-hour internal clock that regulates our sleep and wake cycles. This clock is “set” by light from the environment, and the circadian rhythm also dictates other processes in the body such as food intake, hormone secretion, insulin sensitivity, and energy expenditure.2
What Happens When Your Circadian Rhythm is Disrupted?
Disruptions to your circadian rhythm can result in visible changes to behavior. Studies show that individuals who sleep less than 7 hours per night consume an average of 300-400 extra calories throughout the day, have an increase in preference for snacks over meals, and demonstrate a tendency toward higher fat and higher carbohydrate foods with an overall decrease in protein intake.1,3
In studies controlled for caloric intake, those consuming more of their calories between evening and the following morning were found to have greater weight gain, indicating that timing of food contributes to the body’s ability to digest and utilize it.1 In some individuals lack of sleep can also impact energy expenditure.4,5 In athletes, those who are not well rested are more likely to have negative attitudes toward training and a greater perceived effort at lower levels of performance.5 This means that insufficient sleep can result in reduced performance and lack of improvement in the sport.
Other disruptions to the circadian rhythm are less visible, but just as impactful to health. One well studied impact is insulin resistance brought about by the mistiming of glucose production in the liver, sensitivity of tissue cells to insulin at different times throughout the day, and the intake of carbohydrates in the diet.2 Another studied impact is the changes to levels of the hormones leptin, which suppresses appetite, and ghrelin, which stimulates appetite. Those with shorter sleep duration show reduced levels of leptin and increased levels of ghrelin.1 This can result in increased intakes of energy-dense foods and snacks and difficulty with appetite regulation. Disruptions can even affect the brain reward systems through changes to hormones and neurotransmitters, increasing the reward for eating and choosing highly palatable foods high in sugar, salt, or fat.
What can you do to start getting more sleep?
Getting enough rest can be difficult, especially when an individual is already in a cycle of falling asleep and waking up at irregular times. Studies show that proper nutrition and regular timing of meals can have a significant impact on a person’s ability to fall asleep, stay asleep, and sleep deeply enough to feel rested. There are also behaviors that can be implemented to help your body wind down. Increasing exposure to bright, natural light during the day can improve sleep quality. On the other hand, reducing exposure to blue light from screens on televisions, computers, and smartphones can help a person to fall asleep more quickly.2
Regular exercise also helps to synchronize body tissue clocks and improves sleep quality. Some studies show that meal timing can have an effect too, with positive results coming from populations who eat most of their calories in the morning to afternoon, and from populations who maintain a 12 hour fast between dinner and breakfast (meaning no late night snacks!).2
Are some foods better to eat before bed than others?
Studies also suggest that some specific foods and nutrients can affect sleep duration and quality. Eating higher glycemic index carbohydrates between 4 and 1 hours before bed reduced the time it took to fall asleep in some populations, though others showed that an increased load of carbohydrates before bed reduced sleep quality.5 Additionally, diets higher in protein contributed to better sleep quality and diets higher in fat contributed to lower sleep quality. Those who regularly consumed diets that did not meet their caloric needs saw decreases in sleep quality as well.5
Higher protein diets may result in better sleep because of their contribution to the synthesis of melatonin in the brain. Tryptophan is an amino acid necessary for the synthesis of melatonin, and it requires large neutral amino acids in the blood to help it cross the blood brain barrier. Supplementing tryptophan in doses as small as 1 g can improve subjective sleep quality. Tryptophan can be found in foods such as pumpkin seeds (200 g) and turkey (300 g).5
While the general population is recommended to get at least 7 hours of sleep per night, athletes who exercise at a higher intensity may require 8 or even 9 hours to feel adequately rested and allow their bodies proper recovery. The bottom line: don’t sacrifice your sleep! Not getting enough can significantly undermine your health and fitness goals.
For more information on sleep, visit the links and references below:
- Dashti, H. S., Scheer, F. A., Jacques, P. F., Lamon-Fava, S., & Ordovás, J. M. (2015). Short sleep duration and dietary intake: epidemiologic evidence, mechanisms, and health implications. Advances in nutrition (Bethesda, Md.), 6(6), 648-59. doi:10.3945/an.115.008623
- Stenvers DJ, Scheer FAJL, Schrauwen P, Fleur SEL, Kalsbeek A. Circadian clocks and insulin resistance. Nature Reviews Endocrinology. 2018;15(2):75-89. doi:10.1038/s41574-018-0122-1.
- Khatib HKA, Harding SV, Darzi J, Pot GK. The effects of partial sleep deprivation on energy balance: a systematic review and meta-analysis. European Journal of Clinical Nutrition. 2016;71(5):614-624. doi:10.1038/ejcn.2016.201.
- Capers, P. L., Fobian, A. D., Kaiser, K. A., Borah, R., & Allison, D. B. (2015). A systematic review and meta-analysis of randomized controlled trials of the impact of sleep duration on adiposity and components of energy balance. Obesity reviews : an official journal of the International Association for the Study of Obesity, 16(9), 771-82.
- Halson S. L. (2014). Sleep in elite athletes and nutritional interventions to enhance sleep. Sports medicine (Auckland, N.Z.), 44 Suppl 1(Suppl 1), S13-23.