Sleeping is certainly not a waste of time. During sleep, the brain is in fact very active: it cleaned up from the waste accumulated during the day, consolidates the memories of the day to make room for new memories, and stimulates the production of very important hormones for our health. Among these, the growth hormone (or GH), which regulates muscle growth and helps to burn excess fat. For this reason, a good night of sleep is fundamental for a growing body, such as that of children and teenagers, and for anyone who is trying to put on a little muscles, or lose a few kilo. It is certainly not a mystery, but a new study today helps to clarify some less clear aspects of the sophisticated circuit with which sleep influences the production of the growth hormone, and with which this – in turn – regulates the alternation between sleep and vigil.
The study
The research, published on Cell, focused on the funzification of two molecules that contribute to regulating growth hormone levels in the brain: the GHRH (Growth Hormone – Releasing Hormone) hormone, which stimulates the production by the pituitary gland, and the somatostatine, which inhibit it. Working on mice, the Berkeley researchers team monitored the activity of these two hormones in the brain during REM sleep (the phase in which you dream) and not Rem (the longest phase of sleep in which dreams are not experienced), and the effects that have on brain activity and on the production of growth hormone.
The results revealed an unexpected situation. During the REM phase, in fact, both the levels of Ghrh and the somatostatine levels increase, and in correspondence there is an increase in the production of growth hormone. In sleep, however, the levels of somatostatine collapse, and Ghrh of Ghrh increase in moderately, but the production of growth hormone remains high.
A complex circuit
The high levels of somatostatine identified during the REM sleep phase, in theory, should be incompatible with the production of growth hormone: their function, after all, is to inhibit its secretion. However, the new research has made it possible to better understand its activity, clarifying that somatostatine in the right conditions can act like a metronome, regulating the activity of Ghrh and producing periodic peaks in growth hormone levels. In the non -Rem phase, however, their presence is drastically reduced, and the hormone is therefore produced continuously.
As a conductor, therefore, the two substances act in concert in the brain during sleep to modulate with precision the rhythm with which the growth hormone is produced in the times, and in the quantities, necessary to repair and increase the muscles. This is not all, because the research has also identified a mechanism with which the accumulation of growth hormone in the brain stimulates a region known as Locus Coeruleus, helping to regulate the alternation between sleep and vigil: a gradual stimulation of the Locus Coeruleus promotes in fact, while an overeximulation, on the contrary, promotes sleepingness.
The importance of sleep
“These results suggest that sleep and growth hormone form an extremely compact system: too little sleep reduces the production of the hormone, and too much growth hormone in return pushes the brain to wake up,” explains Daniel Silverman, among the authors of the research. “This balance is essential for growth, repair of muscle tissues and for metabolic health”.
Sleep is therefore confirmed as a fundamental window for the maintenance and growth of our body. Important for the youngest, who have yet to end growth, for athletes and fitness enthusiasts who want to increase their musculature, but also for older people, who must keep bones and muscles compromised by aging healthy. For this reason, the mechanisms brought to light from research could help develop new therapies in the future to improve the quality of sleep and our health. Provided that, of course, the results obtained by working on mice are also confirmed by studying our species.