Can you really catch up on lost sleep?
I have always been a strong believer in and proponent of the recovery power of sleep. It is undervalued, yet so important to our living and performing in a human body from day to day. I recently came across a research article on weekly sleep deprivation and its effects on performance. We’ve all been guilty of overworking and overextending during the week, then ‘catching up’ on sleep over the weekend. Does this strategy actually work? And, if so, in what ways does it work or not work?
In this study, researchers took a group of 30 healthy male and female subjects and looked at 3 phases of sleep pattern:
1) Sleeping 8 hours a night for 4 days
2) Sleeping 6 hours a night for 6 days
3) Sleeping 10 hours for 3 nights
This pattern simulated baseline rest, sleep deprived week and catch sleep on the weekend. Subjects were measured for interleukin-6 (IL-6), cortisol, objective and subjective measures of sleepiness and performance after each of the 3 phases. IL-6 is a pro-inflammatory cytokine. A cytokine is a cell signaling molecule; it is a small protein released by the cells sent to affect the behavior of other cells. An increase in IL-6 means added stress is placed on the body in the form of inflammation. Cortisol is a steroid hormone released by the adrenal glands also present when the body is under stress. Prolonged cortisol secretion is a sign of chronic stress.
Objective sleepiness was measured using a sleep disorder diagnostic tool called Multiple Sleep Latency Test (MLST). Electrodes are attached to subjects’ brains, eyes and muscles to monitor activity through the day and night. Subjective sleepiness was measured using the Stanford Sleepiness Scale (SSS). (How sleepy do you feel right now?)
Performance was measured using a Psychomotor Vigilance Task (PVT). (Note, when I first read the article, I thought how does this test have any bearing on endurance performance? Read on. ) PVT is a simple test where the subject hits a button as soon as a light appears. The light goes on randomly every 5-10 minutes. The test measures how many times the button is not pressed when the light is on. The purpose of the test is to assess sustained attention, i.e. can the subject be vigilant and maintain focus throughout the test. PVT has been used by crewmembers on the International Space Station to assess performance capabilities. If an athlete cannot maintain focus and vigilance in training, fatigue levels are high and performance is impaired.
Researchers concluded that all measurements were elevated or impaired during the sleep deprivation phase: cortisol and IL-6 levels were significantly elevated; both objective and subjective sleepiness measurements were high. The subjects were tired after 4 days of less than ideal sleep. After 2 days of extra recovery sleep, all the elevated levels measured returned to normal. The subjects felt less sleepy and their blood markers proved this fact. Everything went back to normal, except performance. Performance remained impaired even after the recovery sleep phase. “…Two recovery nights were not sufficient to improve performance, suggesting that complete performance recovery following one workweek of sleep restriction may require more than two days of extended sleep.”
While you can make up for extended sleep deprivation with a few days of extra sleep, it is likely that in order to perform physical tasks without impairment, regular daily sleep OR a longer recovery phase is required. Generally, 7-8 hours/day (naps count!) are recommended, but for those training more than 18 hours/week, 9-10 hours are needed.
It’s free and you need it every day. Sleep well.
Article: Pejovic, Slobodanka, et al. The effects of recovery sleep after one workweek on mild sleep restriction on Interleukin-6 and cortisol secretion and daytime sleepiness and performance. Am J Physiol Endocrinol Metab. August 2013. 10-1152