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The hormonal and metabolic processes that occur during sleep

The three primary factors to consider for those seeking muscle hypertrophy are: training, nutrition and recovery. Sleep is an important part of recovery as well as being probably the most underestimated factor with regard to muscle growth, though most of us are guilty of taking sleep offhandedly. Through this article we will see how it’s possible to optimize sleep for hypertrophy and body composition.

Sleep is a very well structured process, and sleeping takes us through two different stages: non-REM (NREM) sleep and REM sleep.

NREM sleep can be subdivided into 4 phases:

From phases 1 to 3 we slip into deeper sleep.

Then during phases 3 and 4 we reach deep sleep – this is when the brain produces delta waves. Phase 4 is also called slow wave sleep (SWS). During SWS your body produces a peak in GH, this is the moment when the body is the most anabolic and protein synthesis and the immune system are working at full rate.

Then comes REM sleep, during which the brain is more active and the body turns catabolic (remember you are either catabolic or anabolic, it is an either / or process). During REM, cortisol levels gradually go up, which will eventually wake you up. In very simple terms, REM is anabolic and favours the muscles, NREM is catabolic and restores brain functions (the construction of new memories as well as the acquisition of new motor skills depend on NREM sleep).

During the night you go through the cycle of NREM (the 4 stages), plus REM, 4 to 6 times depending on sleep duration, and each full cycle lasts from approximately 90 to 110 mins (there are variances between individuals). Each time you go through a complete cycle, the NREM/REM ratio changes, favouring REM as the night advances. At the end of the night, REM lasts about 80mins, and NREM as little as 10 mins (so much for GH secretion and anabolism!).

The processes during sleep are organized and you can’t alter the structure, this is why so many authors emphasize the fact that to achieve ‘quality’ sleep, it must be ‘uninterrupted’ sleep!  We are left to wonder then if waking up after a full cycle (to go to the bathroom for instance, or to gulp down a shake) is as detrimental as waking up mid-may through a cycle…

What about naps?

During a nap the same processes occur, sleep is structured in the same way regardless of duration.

This has implications with regard to how long an optimal nap should last. Don’t venture into deep sleep if you don’t intend to sleep through REM afterwards. In fact, if you are on a tight schedule, then a short nap will be more refreshing than allowing yourself to move to phases 3 and 4 and waking up during that time. An ideal power nap lasts about 20 to 30 minutes (just shy of reaching deep sleep)!

It should be noted that if you generate a sleep deficit, that is, when sleeping less than 7 hours per night consistently, the body will automatically compensate for time lost in REM and subsequently privilege REM sleep at the expense of NREM sleep. So be careful. Don’t tap into the preferred time for anabolism and think you can trick your body into growth easily afterwards as the brain will be privileged at the expense of the body.

There is ample data to show how ugly sleep debt can be. Indeed, too little, or bad quality sleep can lead to:

• Metabolic inflexibility: Lack of sleep entails insufficient production of GH (60 to 90% of GH is produced during SWS). Shortage of GH will lead to metabolic inflexibility, poor glucose metabolism and poor fat oxidation. In a word – poor body composition.

• Increased hunger: Two hormones involved in appetite control Leptin and Ghrelin are thrown out of whack because of lack of sleep. These two, if not well balanced can leave you as ravenous as a bodybuilder after a 16 week cut! Try that kind of hunger level when in a calorie surplus… not pretty! Especially when metabolic flexibility is not at optimal levels!

• Elevated levels of cortisol: Cortisol will likely be chronically elevated throughout the day if you don’t have adequate levels of sleep, but what is worse is that cortisol levels could be doubled post-workout! Hello catabolism!  Bye bye benefits from gruelling workouts!

• Inflammation: Sleep deprived individuals display high levels of inflammatory markers which is very detrimental to hypertrophy.

• Lack of results: A sleep deprived individual has to work twice as hard as would a well rested one to reach the same results in terms of muscle growth or fat loss… so get plenty of sleep!

• Lack of motivation: Sleep deprived individuals lack the drive to workout, the will to follow their schedule, the discipline to stick to their diet and so forth….

So what’s recommended?

• Sleep 7 to 9 hours per night if possible

• Aim for quality sleep, don’t allow your sleep to be interrupted

• Eat right before bedtime, take carbs before bed if you can “afford it”, as they promote sleep. Eat slow digesting protein that will be used during the night during the most anabolic phases.

• Take naps and try to account for the structure of sleep (20 to 30 min naps, or go for a full cycle and shoot for 90-110min naps!).

References

1) International Journal of Endocrinology Volume 2010 (2010), Article ID 270832, 12 pages http://www.hindawi.com/journals/ije/2010/270832/

2) Mountain Dog Diet February 2013: Sleep Like A Dog! (Grow Like a Weed?)

by Scott Stevenson PhD, LAc

3) ABC Bodybuilding.com

http://www.abcbodybuilding.com/zfactor.pdf

4) Poliquin Podcast Sleep

5) http://www.webmd.com/sleep-disorders/excessive-sleepiness-10/lack-of-sleep-weight-gain

6) http://www.medscape.org/viewarticle/502825