Sleep is important in regulating metabolism. Sleeping mammals can be divided into two distinct phases - REM (rapid eye movement) and non-REM (NREM) sleep. In humans and cats, NREM sleep has four stages, where the third and fourth stages are considered slow-wave sleep (SWS). SWS is considered to sleep well, when metabolism is least active.
Metabolism involves two biochemical processes that occur in living organisms. The first is anabolism, which refers to the formation of molecules. The second is catabolism, the breaking of molecules. Both of these processes work to regulate the amount of energy the body uses to defend itself. During non-REM sleep, the metabolic rate and temperature of the brain are lowered to deal with damage that may occur during awake time.
Video Sleep and metabolism
Normal metabolism
After eating, the pancreas releases insulin. Insulin gives muscle and fat cell signals to absorb glucose from food. As a result, blood glucose levels return to normal.
Maps Sleep and metabolism
Lack of sleep and type 2 diabetes
Insulin-Resistant Metabolism
Baseline levels of insulin do not signal muscles and fat cells to absorb glucose. As the glucose level rises, the pancreas responds by releasing insulin. Blood sugar will quickly go down. This can lead to type 2 diabetes.
Sleep loss can affect the basic metabolic functions of storing carbohydrates and regulating hormones. Sleep deprivation from eight hours to four hours results in changes in glucose tolerance and endocrine function. Researchers from the University of Chicago Medical Center followed 11 healthy young men for 16 consecutive nights. The first 3 nights, the youth sleep for 8 hours normally. The next 6 nights, they slept for 4 hours. 7 next night, they spent 12 hours in bed. They all have the same diet. They found that there was a change in glucose metabolism similar to that of type 2 diabetic patients. When participants were tested after sleep deprivation, they took 40% longer than usual to regulate blood sugar levels after eating high carbohydrates. Insulin secretion and the body's response to insulin decreased by 30%. Lack of sleep also alters hormone production, decreases thyroid stimulating hormone secretion and increases cortisol levels in the blood.
It has also been shown that when slow-wave sleep is suppressed for three nights, a healthy young subject is 25% less sensitive to insulin. They need more insulin to get rid of the same amount of glucose. If the body does not release more insulin to be compensated, blood glucose levels will increase. It resembles impaired glucose tolerance, which can lead to type 2 diabetes.
Lack of sleep and appetite control
Sleep plays an important role in regulating metabolism and appetite. When lack of sleep, the metabolic system will be unbalanced, which will ultimately affect the dietary choices people make. Sleeping teenagers crave more carbohydrates. Sleep deprivation is a risk factor for obesity among young adults.
There are two hormones, leptin and ghrelin, which are important in controlling appetite. Leptin, released by adipose tissue, is a hormone that inhibits appetite and increases energy expenditure. Ghrelin, released from the stomach, is a hormone that increases appetite and reduces energy expenditure. Lack of sleep can cause a 19% decrease in leptin levels. Subjects were deprived of sleep for 2 nights (4 hours per night) and got sleep compensation for the next 2 nights (10 hours per night). Leptin levels decreased by 18% and ghrelin levels increased 28%. There is an increase in the level of hunger by 23 which may be caused by leptin levels of reduction. Subjects also prefer high carbohydrate foods (sweets, salty foods and starchy foods). The desire for salty food increased by 45%. Lack of sleep can cause people to intake food for emotional/psychological needs rather than the caloric needs of the body.
Chronic sleep deprivation (less than 8 hours sleep) is associated with an increase in body mass index (BMI). In a Wisconsin sleep cohort study of 1,024 patients, shorter sleep durations showed decreased levels of leptin and elevated ghrelin levels. In a study with 3000 patients, it has been found that men and women who slept less than 5 hours experienced an increase in body mass index (BMI). In another study that followed about 70,000 women for 16 years, there was a significant weight gain in those who slept 5 hours or less compared to those who slept 7-8 hours.
As bedtime declined over time from 1950 to 2000s from about 8.5 hours to 6.5 hours, there has been an increase in the prevalence of obesity from about 10% to about 23%.
References
Source of the article : Wikipedia
0 Comments