Sleep is an essential function that allows the body and mind to recharge, leaving one refreshed and alert on waking up. Thus sleep plays a vital role in good health and well-being throughout life. Getting enough quality sleep at the right times can help protect mental health, physical health, quality of life, and satiety. Sleeping impacts many physiological and psychological processes. Researchers believe that sleep may promote the removal of waste products from brain cells, thus restoring brain energy and consolidating information into memory.
Sleeping at night helps align the body’s internal clock (circadian rhythm), with its environment. Proper circadian timing is important for sleep quality and affects mental health, cardiovascular function, metabolism, and our ability to fight chronic disease risk and develop immunity.
Several prominent theories have explored the brain and attempted to identify a purpose for why we sleep, which include the Inactivity theory, Energy conservation theory, Restoration theory, and Brain plasticity theory (neural growth of brain’s structure and function).
RECOMMENDED SLEEP TIME PERIOD*
Category | Age | Sleep Hours (Ideal Range) |
Newborn | 0-3 months | 14-17 hr/24h |
Infant | 4-12 months | 12-16 h/24h |
Toddler | 1-2 yr | 11-14 h/24h |
Preschooler | 3-5 yr | 10-13 h/24h |
School-aged | 6-13 yr | 9-12 h/24h |
Teenager | 14-17 yr | 8-10 h/24h |
Adult | 18-64 yr | 7-9 h/24h |
Older adult | > 65 yr | 7-8 h/24h |
Also Read: Osteoarthritis: Important Foods, Vitamins, Minerals, and Enzymes to Maintain Joint Health
CO-RELATION OF SLEEP WITH DIABETES AND HEART RISK FACTORS
There is an emerging consensus that sleeping less or having disrupted sleep affects brain function, imbalances the hormones and increases inflammation. All these factors can negatively affect our blood glucose levels. Less than 6 hours of night sleep is correlated with an increased risk for developing pre-diabetes, diabetes, and associated diseases (blood pressure, obesity, and heart problems). It has been proved in a repeated pilot study on healthy adult people which showed a reduction in the body’s ability to bring down blood glucose levels after drinking a glass of glucose water. The same subjects when slept on recommended sleep hours, and their blood glucose returned to normal.
Poor sleep can also cause unnecessary activation of the immune system, unbalancing another brain hormone-hypocretin, responsible for only the right types of immune cells being released. This imbalance contributes to diabetes and its complications including heart diseases.
CO-RELATION OF SLEEP HORMONE (MELATONIN) AND SATIETY HORMONES (GHRELIN, LEPTIN) WITH DIABETES
The brain is the master regulator of almost all hormones in the body. Sleep loss changes the level or timing of melatonin, a sleep hormone. Melatonin is responsible for putting the brain to sleep. This hormone also affects the normal function of the pancreas. After a good sleep overnight, melatonin level is low in the morning and the brain feels afresh.
But in poor night’s sleep, melatonin level is still high in the morning and it takes a longer period of hours to come down. This prevents the pancreas from releasing enough insulin to deal with breakfast, leading to a start of the day with an increased blood sugar level. This results in the pre-diabetic condition and type 2 diabetes in due course of time.
Less sleep directly affects the hunger and satiety hormones (ghrelin, leptin), both are controlled by the biological clock in the brain (circadian cycle). Ghrelin is produced in the stomach when it is empty and leptin is produced in fat cells and signals the brain that you are full. Poor sleep patterns disrupt this clock, causing an imbalance between the two hormones. The gut starts craving for heavy breakfast and bigger carbohydrates in the morning which affects the blood sugar. At the same time stress hormone, cortisol also increases which reduces the effect of insulin, and blood glucose level rises.
Thus sleep is not a shutting down of bodily functions; instead lets the whole body reset by repairing and storing cells to perform essential functions to maintain a healthy life, mentally and physically.