If you’ve been pursuing an aesthetic physique for any measure of time you’ve likely heard how important it is to dial in your training and diet. Although these are critical aspects, one topic that doesn’t receive the attention it deserves is proper recovery—specifically when it comes to sleep.
Most people can appreciate the importance of sleep on a superficial level but often aren’t aware of just how detrimental sleep deprivation (SD) can be on body composition. A 2010 study entitled “Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity” came to some pretty startling conclusions that may have significant implications on aspiring bodybuilders and physique athletes. The intervention had two groups, both of which maintained equated caloric restrictions. One group had 8.5 hours of bed rest and the other was restricted to 5.5 hours. The length of the intervention spanned fourteen days.
The researchers found that although the total weight loss was virtually identical between both groups the sleep restricted group lost 60% more lean mass than the other control group. Sleep restriction “decreased the fraction of weight lost as fat by 55%”.1 This is a massive difference in body composition outcomes.
The design of the study was well constructed, however, there was no resistance training protocol which is worth mentioning. It’s likely that if both groups were engaged in a resistance training program during this intervention the total amount of lean mass lost would be reduced. But in my estimation, the results would still favor the longer bed rest group.
So why was there such a dramatic difference in body composition between groups? What are the actual mechanisms involved and were there any indirect factors associated with each outcome? Let’s explore this in more depth to gain a better understanding of the implications of sleep deprivation on body composition and the measures you can take to prevent its occurrence.
1. Neuroendocrine Response and Hunger Signaling
Your neuroendocrine systems play a major role in regulating your physiological and/or behavioral state.2 Sleep deprivation triggers a response from your neuroendocrine system that results in a cascade of biochemical reactions which increase hunger signaling, specifically for high sugar, high-fat foods.3 During sleep deprivation, your subjective feelings of fatigue increase, as a response appetite can increase to provide more energy for your body to function. If you are dieting and trying to maintain a caloric deficit this response presents a significant obstruction to dietary adherence.
2. Muscle Catabolism
Sleep deprivation also has very powerful catabolic effects (tissue breakdown). One of the adaptive responses to sleep deprivation is reduced resting metabolic rate (RMR) along with increased ghrelin concentrations which promote fat retention. In this physiological state muscle catabolism becomes a significant risk if you are in a caloric deficit.1 In the above intervention, the sleep deprivation group lost substantially more lean tissue. We know that fat mass has a higher energy density than lean mass, so the fact that the total weight loss across both control groups was virtually identical suggests that the longer bed rest group maintained a higher RMR.
3. Increased Ghrelin and Fat Retention
Increased ghrelin concentrations are one of the neuroendocrine responses to sleep deprivation. As mentioned above, ghrelin can increase hunger signaling, but it can also increase fat retention. If in a caloric deficit there is an increased risk of changes in body composition that preference retention of adiposity over lean mass.4
4. Decreased Resting Metabolic Rate
RMR is your body’s daily energy requirement at complete rest. Total daily energy expenditure (TDEE) is your RMR plus any additional energy expenditure that occurs throughout the day (ie. walking, sitting, working, exercising, eating, etc). Sleep deprivation acutely decreases RMR5 and often negatively impacts TDEE because of an increase in subjective ratings of fatigue that may result in decreased desire to be physically active.
5. Decreased Performance and Increased Risk of Injury
Although performance isn’t a metric bodybuilders are judged on in competition, certain performance metrics are directly linked to hypertrophy. Sleep deprivation has been shown to impede several performance metrics along with varying timelines. The first performance outcomes that seem to be impacted are explosive power, speed, response time, and coordination.6 This is significant because if response time and motor control are impeded during strenuous physical training it can increase the risk of injury. Strength qualities seem to be retained for longer but eventually the same drop off in performance is observed.
6. Decrease In Mood and Motivation to Train
Interestingly, sleep deprivation states can result in decreased performance especially at submaximal loads due to its negative impact on mood 7, 8 which may decrease intrinsic motivation to train. This is especially applicable to bodybuilders because the majority of hypertrophy training typically occurs between the 60-80% 1RM range.
Preventative Measures to Minimize Sleep Deprivation
Now that we’ve established just how impactful sleep deprivation can be on body composition, it’s time to look at potential preventative measures you can implement to minimize the above risks.
- Ensure you’re sleeping eight hours every night. More is often better and there doesn’t appear to be any downsides to sleep extension, however significant benefits to performance and cognitive ability have been reported in the literature.9
- If sleeping for eight hours daily is not feasible due to individual circumstances, planning routine naps into your day does a good job of minimizing the risk of SD.10
- Maintain a consistent sleep schedule when possible. Some people are early risers and others function better at night. Regardless of where you fall on the spectrum, continuity is a great teaching tool for your body and can help regulate predictable sleep patterns. Research on irregular sleep times also finds a strong correlation to increased SD when compared to a congruent sleep schedule.11
- If stress is a potential obstruction to sleep length or congruency developing a plan to reduce stress can have a significant impact. If you are prone to anxiety and stress, reducing intake of stimulants (ie. caffeine, pre-workouts, etc.) may reduce sympathetic activity and diminish subjective feelings of stress and anxiety.12
By implementing the above strategies you can be fairly certain that you’ll minimize any potential risk for SD and its negative impact on body composition.
Good luck and lift big!
References:
1. Nedeltcheva, Arlet V., et al. “Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity.” Annals of Internal Medicine, vol. 153, no. 7, May 2010, p. 435., doi:10.7326/0003-4819-153-7-201010050-00006.
2. Levine, Jon E. “An Introduction to Neuroendocrine Systems.” Handbook of Neuroendocrinology, 2012, pp. 3–19., doi:10.1016/b978-0-12-375097-6.10001-0.
3. Spiegel, Karine, et al. “Brief Communication: Sleep Curtailment in Healthy Young Men Is Associated with Decreased Leptin Levels, Elevated Ghrelin Levels, and Increased Hunger and Appetite.” Annals of Internal Medicine, vol. 141, no. 11, July 2004, p. 846., doi:10.7326/0003-4819-141-11-200412070-00008.
4. Scrimshaw, N. S., et al. “Effects of Sleep Deprivation and Reversal of Diurnal Activity on Protein Metabolism of Young Men.” The American Journal of Clinical Nutrition, vol. 19, no. 5, Jan. 1966, pp. 313–319., doi:10.1093/ajcn/19.5.313.
5. Spaeth, Andrea M., et al. “Resting Metabolic Rate Varies by Race and by Sleep Duration.” Obesity, vol. 23, no. 12, May 2015, pp. 2349–2356., doi:10.1002/oby.21198.
6. Mah, Cheri D., et al. “Sleep Restriction Impairs Maximal Jump Performance and Joint Coordination in Elite Athletes.” Journal of Sports Sciences, vol. 37, no. 17, 2019, pp. 1981–1988., doi:10.1080/02640414.2019.1612504.
7. Reilly, Thomas, and Mark Piercy. “The Effect of Partial Sleep Deprivation on Weight-Lifting Performance.” Ergonomics, vol. 37, no. 1, 1994, pp. 107–115., doi:10.1080/00140139408963628.
8. Pilcher, June J., and Allen I. Huffcutt. “Effects of Sleep Deprivation on Performance: A Meta-Analysis.” Sleep, vol. 19, no. 4, 1996, pp. 318–326., doi:10.1093/sleep/19.4.318.
9. Mah, Cheri D., et al. “The Effects of Sleep Extension on the Athletic Performance of Collegiate Basketball Players.” Sleep, vol. 34, no. 7, 2011, pp. 943–950., doi:10.5665/sleep.1132.
10. Haslam, Diana R. “Sleep Deprivation and Naps.” Behavior Research Methods, Instruments, & Computers, vol. 17, no. 1, 1985, pp. 46–54., doi:10.3758/bf03200896.
11. Kang, Jiunn-Horng, and Shih-Ching Chen. “Effects of an Irregular Bedtime Schedule on Sleep Quality, Daytime Sleepiness, and Fatigue among University Students in Taiwan.” BMC Public Health, vol. 9, no. 1, 2009, doi:10.1186/1471-2458-9-248.
12. Sawyer, Deborah A., et al. “Caffeine and Human Behavior: Arousal, Anxiety, and Performance Effects.” Journal of Behavioral Medicine, vol. 5, no. 4, 1982, pp. 415–439., doi:10.1007/bf00845371.