The following is a continuation of my last post on the same topic – sleep as the primary producer of recovery for athletes. Both are excerpts from a book I’m currently writing with the working title of Fast After 50. In the Part 1 post a reader caught a mistake I made relative to slow wave sleep. It should have said … “the frequency of the brain’s electrical activity becomes quite slow.” I had said “the amplitude of the brain’s…” I corrected it. These are the sorts of things that usually go uncaught until the final product is on the bookshelves. Your input is always appreciated and taken seriously. It’s too bad I can’t post the entire book here for you to read and comment on as that would make it a much better product, but I don’t think my publisher would be too keen on that. I have just one more chapter to write, a few problems to clear up and then it will be ready for editing and, eventually, publishing. While I’ve learned a lot, it’s been a challenge to write and I’ll be glad to get a break before starting on my next project (more on this later). It’s been a huge project as a paragraph can sometimes take an hour to write because of all of the research checking needed. But I love doing that. Here’s Part 2 of Sleep and Recovery.
While there is still a lot to be learned about sleep, it appears that each stage has a specific, essential purpose. The two with which we are most concerned now are the REM and slow wave (N3) stages.
REM is the truly high quality stage of sleep when a lot of important recovery stuff happens. REM is also when you do most of your memorable dreaming. This stage lasts for a few minutes at a time and makes up 20 to 25 percent of your sleep time if you have a full night of sleep. REM happens about every 90 minutes to two hours with non-REM or brief awakenings making up the in-between times. During REM the tissue-building hormones testosterone and estrogen are released into the body to aid recovery. These hormones are categorized as anabolic steroids meaning that they promote tissue, muscle and bone growth and repair. They also have a positive effect on the cellular properties that improve endurance performance. Testosterone is the more potent of these two. Men produce about 20 times as much testosterone as women, but women’s bodies are more sensitive to it. Since REM occurs late in a night’s sleep cycle, artificially shortening your sleep by awakening to an alarm clock may well diminish the release of these hormones thus hindering full recovery.17,18 The negative results may not be too great after a night or two of this, but chronically shortening your natural sleep cycle is likely to have a long-term effect on training quality and performance.
The other critical sleep stage for recovery is slow wave (N3) that generally starts around an hour after falling asleep and recurs several times during the first half or so of the night. During this time your body experiences a rush of growth hormone (GH) that also promotes muscle growth and bone repair among other things. Nearly half of your daily GH secretion occurs during this stage.19 Short of losing an entire night of sleep, you’re unlikely to miss your daily dose of growth hormone. But since aging reduces the total amount of growth hormone your body produces you can’t afford to miss any sleep at all.20,21,22 Unfortunately, slow wave sleep duration is shortened in older folks as we tend to wake up more often.23 In college-aged youth, slow-wave sleep makes up about 19 percent of their sleep time. For us old folks it’s more like three percent.20
Overall, with aging there is a tendency for an earlier sleep onset in the evening, an earlier morning awakening and more fragmented and shallow sleep throughout the night. This further decreases the release of the anabolic hormones testosterone and GH.
Another hormone is released into the blood stream while we sleep—cortisol.24 Its primary function is to prepare the body to cope with stress by increasing blood sugar (we’ll investigate the downsides of this in Chapter 8) and compromising the immune system. It’s also been shown to slow the healing of injuries25 and decrease bone formation.26 All of this hormone stuff makes for a double whammy.
To help maximize sleep time there are several things you can do besides wearing blue-blocking glasses in the evening, which may make you feel a bit weird. I expect you are already familiar with the most common ones—avoiding caffeine in the late afternoon and evening, not working out intensely in the four hours or so before bedtime, maintaining a calm and quiet environment before going to bed, following a regular sleep schedule and bedding down in a dark and cool room. But there are others.
Go light on alcohol in the evening as it has a rebound effect that can wake you later from an otherwise sound sleep. While alcohol doesn’t seem to negatively affect slow wave sleep, and may even be beneficial for it, it has been shown to reduce REM sleep duration.27 I also know of some who take a melatonin supplement in the evening to promote drowsiness. I wouldn’t recommend that as typically when a supplement is used to exogenously (from outside the body) promote some functional change, the body responds by reducing or even halting its natural production of the targeted product and by becoming less sensitive to it. A strange alternative solution that some studies have found and confirmed is drinking a glass of tart cherry juice in the evening. I know that sounds weird, but it seems to work. The aging subjects in these studies had an increase in melatonin production and improved sleep compared with a placebo.28,29,30
When you eat and what your evening meal is made up of may also affect your night-time sleeping. As your mom told you when you were a kid (of course, you didn’t believe her then): a late evening meal or pre-bedtime snack reduces sleep quality.31 So don’t chow down right before going to bed. One study, and I want emphasize only one so far, has shown that the foods you eat late in the day may affect how well you sleep.32 University of North Dakota researchers looked at which type of food was most likely to improve sleep, and, conversely, which may have negative consequences for snoozing. Forty-four adults ate either a high-protein, high-fat, high-carbohydrate or a balanced control diet before retiring for the evening. They did this over a four-day period and crossed over so that each subject ate all of the four meal types. They went to bed after each of the meals and their sleep quality was observed. When eating the high-protein meal their sleep had the fewest interruptions. The high-carb meals produced the least restful sleep.
I want to once again emphasize that sleep is the single most important thing you can do to speed your recovery in order to produce high-quality training while avoiding setbacks due to injury, illness and overtraining. The next most important producer of recovery is nutrition. That’s where we’re headed next.
17. Penev PD. 2007. Association between sleep and morning testosterone in older men. J Sleep 30(4):427-32.
18. Penev P, Spiegel K, L'Hermite-Balériaux M, et al. 2003. Relationship between REM sleep and testosterone secretion in older men. Ann Endocrinol 64(2):157.
19. Mehta A, Hindmarsh PC. 2002. The use of somatropin (recombinant growth hormone) in children of short stature. Paediatr Drugs 4(1):37-47.
20. Van Cauter E, Leproult R, Plat L. 2000. Age-related changes in slow-wave sleep and REM sleep and relationship with growth hormone and cortisol levels in healthy men. J Amer Med Assoc 284(7):861–868.
21. Oh MM, Kim JW, Jin MH, et al. 2012. Influence of paradoxical sleep deprivation and sleep recovery on testosterone level in rats of different age. Asian J Androl 14(2):330-4.
22. Antines IB, Andersen ML, Baracat EC, Tufik S. 2006. The effects of paradoxical sleep deprivation on estrous cycles of the female rat. Horm Behav 49(4):433-40.
23. de la Calzada MD. 2000. Modifications in sleep with aging. Rev Neurol 30(6):577-80.
24. Copinschi G, VanCauter E. 1995. Effects of aging on modulatiuon of hormonal sevretions by sleep and circadian rhythmicity. Horm Res 43(1-3):20-4.
25. Ebrecht M, Hextall J, Kirtley L, et al. 2004. Perceived stress and cortisol levels predict speed of wound healing in healthy male adults. Psychoneuroendocrinology 29(6)798-809.
26. Knight RP, Kornfeld DS, Glaser GH, Bondy PK. 1955. Effects of intravenous hydrocortisone on electrolytes of serum and urine in man. J. Clin. Endocrinol. Metab. 15(2):176-81.
27. Ebrahim IO, Shapiro CM, Williams AJ, Fenwick PB. 2013. Alcohol and sleep I: effects on normal sleep. Alcohol Clin Exp Res 37(4):539-49.
28. Howatson G, Bell PG, Tallent J, et al. 2012. Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality. Eur J Nutr51(8):909-16.
29. Pigeon WR, Carr M, Gorman C, Perlis ML. 2010. Effects of a tart cherry juice beverage on the sleep of older adults with insomnia: a pilot study. J Med Food 13(3):579-83.
30. Garrido M, González-Gómez D, Lozano M, et al. 2013. A Jerte valley cherry product provides beneficial effects on sleep quality. Influence on aging. J Nutr Health Aging 17(6):553-60.
31. Crispim CA, Zimberg IZ, dos Reis BG, et al. 2011. Relationship between food intake and sleep pattern in healthy individuals. J Clin Sleep Med 7(6):659-64.
32. Lindseth G, Lindseth P, Thompson M. 2013. Nutritional effects on sleep. West J Nurs Res 35(4):497-513.