Busy professionals like us often have to struggle to squeeze in exercise in between our hectic working schedules and family lives. Which means that we often have to sacrifice our sleeping time. There is enough evidence to show how sleep deprivation can affect performance. But little was known that it also has adverse effect on your body composition. Evidence has linked sleep loss to hormonal changes that could result in obesity, besides causing important neurocognitive changes, including excessive daytime sleepiness and altered mood. Researchers from Eastern Virginia Medical School examined the association between restricted sleep and obesity in a heterogeneous adult primary care population. This study involved a whopping 1001 patients! Patients completed a questionnaire administered by a nurse or study coordinator concerning demographics, medical problems, sleep habits, and sleep disorders. The relationship between body mass index (BMI) and reported total sleep time per 24 hours was analyzed after categorizing patients according to their BMI. This study found that overweight and obese patients slept less than patients with a normal BMI.

And why is that so? You see, what happens when we sleep? First, let me give you an overview of the stages of sleep. Human sleep has been described as a succession of five recurring stages: four non-REM stages and the REM stage. A sixth stage, waking, is often included. Waking, in this context, is actually the phase during which a person falls asleep. Rapid eye movement (REM) sleep is marked by extensive physiological changes, such as accelerated respiration, increased brain activity, eye movement, and muscle relaxation. People dream during REM sleep, perhaps as a result of excited brain activity and the paralysis of major voluntary muscles.

Non-REM Sleep

The period of non-REM sleep (NREM) comprises stages 1-4 and lasts from 90 to 120 minutes, each stage lasting anywhere from 5 to 15 minutes. Surprisingly, however, stages 2 and 3 repeat backwards before REM sleep is attained. So, a normal sleep cycle has this pattern: waking, stage 1, 2, 3, 4, 3, 2, REM. Usually, REM sleep occurs 90 minutes after sleep onset.

Stage 5, REM

REM sleep is distinguishable from NREM sleep by changes in physiological states, including its characteristic rapid eye movements. However, polysomnograms show wave patterns in REM to be similar to Stage 1 sleep. In normal sleep (in people without disorders of sleep-wake patterns or REM behavior disorder), heart rate and respiration speed up and become erratic, while the face, fingers, and legs may twitch. Intense dreaming occurs during REM sleep as a result of heightened cerebral activity, but paralysis occurs simultaneously in the major voluntary muscle groups, including the submental muscles (muscles of the chin and neck). Because REM is a mixture of encephalic (brain) states of excitement and muscular immobility, it is sometimes called paradoxical sleep. It is generally thought that REM-associated muscle paralysis is meant to keep the body from acting out the dreams that occur during this intensely cerebral stage. The first period of REM typically lasts 10 minutes, with each recurring REM stage lengthening, and the final one lasting an hour.

Human Growth Hormone and REM sleep

As much as 90% or more of all human Growth Hormone [hGH] is released in 5 short pulses during deep stage REM sleep. (It is also released after exercise). If you regularly short-change yourself in the sleep department, your secretion of [hGH] will be less than optimal. What is human growth hormone? It is a protein comprised of over one-hundred amino acids that is produced in your pituitary gland that among other things, stimulates the liver to produce insulin-like polypeptides called somatomedins and causes the production of insulin-like growth factor-1 (IGF-1). Human growth hormone [hGH] is the most abundant hormone produced by the pituitary gland in the brain. Simply put, since [hGH] stimulates the repair of tissue damage, rebuilds and restores critical muscle protein, and is integral in the synthesis of immune system antibodies, the amount of [hGH] you have floating around in your bloodstream will largely decide how effectively you recover, adapt, avoid viral infection, and improve from your daily training. More than that, it seems it also has a dramatic effect on how much body fat you carry on your hips and waist. You may want to look at your grandpa whose hGH production has probably declined by more than half the level it was when he was still in his teens. You may notice those unwanted spare tires and love handles! This is just to illustrate how important hGH is in maintaining your body composition and preserving lean muscle mass.