“The functions of sleep are not fully understood or fully explained by science and this has led to the undervaluation of sleep by health professionals. Traditionally thought is that perhaps inactivity was a survival mechanism during the vulnerable period of night or a way to conserve energy, but more recent research suggests that sleep is a complex combination of restoration for both the body and more importantly, the brain (Why Do We Sleep, Anyway?).
There are 4 stages of sleep, light sleep or NREM 1, NREM 2, which is slightly deeper sleep in which heart rates slows and blood pressure decreases. NREM 3 is when brain waves slow and cellular repair happens; it is also when hormone secretion peak and the immune system is most active (Clayton, p. 25). During the last stage of sleep, REM, brain activity resembles that of waking hours dreaming takes places which helps process emotions, makes new neural connections and removed unnecessary ones, and the brain stores memories (Clayton, p. 27). A research study done at Bar-Ilan University in Israel used zebrafish, which are transparent, and examined their neurons while sleeping, showing that Dna damage that builds up during waking hours can only be repaired during periods of sleep (Sleep tight!) Professor Appelbaum, the lead researcher on the study, likens this activity to fixing pothole, “Roads accumulate wear and tear, especially during daytime rush hours, and it is most convenient and efficient to fix them at night, when there is less traffic.” Without sleep, DNA damage in brain cells can build up, with possible results being memory issues, dementia, and even Alzheimer’s disease.
Another brain system that is more active during sleep is the brain’s glymphatic system, which is similar to the lymphatic system, but named for the glial cells in the brain that control it and which is ten times more active during sleeping hours(Clayton, p. 26) Sleep is imperative to immune system functioning as well; the stresses of everyday life stimulate the sympathetic nervous system, which in turn, suppresses the immune system and this is why, during sleep, the immune system is at its most active, and natural killer cells are able to do their work, the body is repaired, and inflammation decreases ( Wilson and Brooks, P 7). Sleep stage 3, when brain waves are the slowest, the immune system is also able to form “memories” that enable it to respond to pathogens better in future encounters, if sleep is impaired these memories may not be made and in some cases the immune system may lose some of its ability to tell the difference between normal cells and pathogens, leading to autoimmune disease (Wilson and Brooks, p. 20).
The effects of sleep deprivation are also less obscure and include increased pain levels, longer recovery times, delayed wound healing and a general lack of wellbeing. In addition, when sleep problems cause the body’s circadian rhythm to be out of sync, hormone release is affected, resulting in an increase in hunger hormones and increased blood glucose levels; this provides insight as to how sleep and certain health condition s such as diabetes mellitus, cardiovascular disease and obesity may be intertwined (Calyton, p 26). Sleep deprivation is also linked, whether as a cause of or a result of, all major psychiatric conditions, including depression (p. 25).
The suggestions that sleep affects all aspects of health including mental health, immune function, recovery, memory, chronic disease and even mortality, indicates that sleep deficiencies are an under recognized public health problem that all health providers need to be aware of and work to remedy. “