The Chemistry Of Sleep
Wednesday, February 01, 2017
Melatonin is a hormone that is a precursor to good sleep. In most people, endogenous melatonin levels are highest during the normal hours of sleep, increasing rapidly in the late evening, then peaking after midnight and decreasing toward morning. Functions of melatonin include: synchronizing circadian and circannual rhythms, which stimulates immune function, and, as has recently been shown is a potent hydroxyl radical scavenger and antioxidant. Melatonin release naturally increases in the late evening. If we arrange our schedules so that we can go to bed in sync with this natural increase, we will maximize its release and the subsequent benefits. On the other hand, if we keep the lights on and stay up in the evening, melatonin release will be reduced and it will be more difficult to enjoy quality sleep.
Ghrelin is a hormone that plays an important role in the regulation of appetite. Research has found that partial sleep deprivation was associated with a decrease in plasma levels of leptin and an accompanying increase in plasma levels of ghrelin. Subjective ratings of hunger and appetite also increased. Moreover, a remarkable correlation was found between the increase in hunger and the increase in the ghrelin/leptin ratio. Thus the neuroendocrine regulation of appetite and food intake appears to be influenced by how long a person sleeps. Studies show that not enough sleep could lead to obesity.
Ghrelin also plays an important role in carbohydrate and lipid metabolism and, possibly, heart function, immune functions, and cell proliferation. It promotes slow-wave sleep (SWS, non-REM sleep stages three and four). Ghrelin also stimulates a growth hormone. Researchers have found that ghrelin levels increase during the early part of the night, with highest levels in the evening and early morning before two a.m. There is then a decrease in the morning. The nocturnal increase was blunted during sleep deprivation, and ghrelin levels increased only slightly until the early morning. The secretion of ghrelin during the first hours of sleep correlated positively with peak human growth hormone concentrations.
When you were young, your mother told you that you need to get enough sleep to grow strong and tall. She was right! Deep sleep triggers a greater release of growth hormone, which fuels growth in children and boosts muscle mass and the repair of cells and tissues in children and adults.
Repairing cells and tissues assists our body in keeping well. A study using growth hormone in HIV patients showed apparent reversal of wasting syndrome, a loss of 10% or more of body weight and restoration of lean body mass.
Most of the physiologically important GH secretion occurs as several large pulses or peaks of GH release each day. The largest and most predictable of these GH peaks occurs about an hour after onset of sleep. This is partly due to the fact that the secretion of GH is strongly associated with deep, non-REM sleep. Deep non-REM sleep, as was noted, takes place more in the early hours of the night and diminishes as the morning approaches. This relationship again demonstrates the importance of getting to bed as early as possible in the evening. By doing so, you will maximize the secretion of GH which will help improve and maintain your health in many ways.