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Sleep Deprivation and Type 2 Diabetes
Baseline levels of insulin do not signal muscle and fat cells to absorb glucose. When glucose levels are elevated, the pancreas responds by releasing insulin. Blood sugar will then rapidly drop. This can progress to type 2 diabetes.
Contents
- Sleep Deprivation and Type 2 Diabetes
- Lack of Sleep Related to Weight Gain
- Can Sleeping More promote Weight Loss
- Effect of Oversleeping
- Obesity Related Sleep Disorders
- Sleep in the Media
- References
Sleep loss can affect the basic metabolic functions of storing carbohydrates and regulating hormones. Reduction of sleep from eight hours to four hours produces 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 young men slept for the normal 8 hours. The next 6 nights, they slept for 4 hours. The next 7 nights, they spent 12 hours in bed. They all had the same diet. They found that there were changes in glucose metabolism that resemble that of type 2 diabetes patients. When the participants were tested after sleep deprivation, they took 40% longer than normal to regulate blood sugar levels after a high-carbohydrate meals. The secretion of insulin and the body's response to insulin decrease by 30%. Sleep deprivation also alters the productions of hormones, lowering the secretion of thyroid stimulating hormone and increasing blood levels of cortisol.
It has also been shown that when slow-wave sleep was suppressed for three nights, young healthy subjects were 25% less sensitive to insulin. They needed more insulin to get rid of the same amount of glucose. If the body does not release more insulin to compensate, the blood-glucose levels will increase. This resembles impaired glucose tolerance, which can result in type 2 diabetes.
Lack of Sleep Related to Weight Gain
There is a strong association between a lack of sleep and weight gain that spans across age, which has been evidenced by several epidemiological surveys. Sleep deprivation and its link to obesity affects both adults and children. Still, the effect of reduced sleep duration on obesity has been reported to be even more significant in children, who are more vulnerable to its effect. Because sleep is very crucial to brain development, which is occurring most rapidly in children and young adults, a lack of sleep can alter the mechanism in the hypothalamus that controls appetite and monitors energy expenditure. Regardless of age however, several changes occur in the body when one is sleep deprived that facilitates weight gain. Some of those changes include increased food consumption and alterations in the amount of appetite-regulation hormones, which include Leptin and Ghrelin.
Matthew P Walker, a psychology and neuroscience professor at UC Berkley published a study during which the participants were deprived of sleep for one night. The New York Times summarized his study as such, "On days when the subjects had not had proper sleep, fattening foods like potato chips and sweets stimulated stronger responses in a part of the brain that helps govern the motivation to eat. But at the same time, the subjects experienced a sharp reduction in activity in the frontal cortex, a higher level part of the brain where consequences are weighted and rational decisions are made.” A brain that has been deprived of sleep for one night is more likely to respond more intensely to junk food but also has the decreased ability to curb that desire. These results were consistent regardless of the amount of energy expended during those extra hours that the subjects stayed awake, which indicates that one’s craving for junk food is not a response to offset an energy deficit. The lack of a link between increased energy expenditure and increased food consumption to facilitate increased wakefulness was further evidenced in the Sleep Debt and Obesity article published in the Annals of Medicine. The article reports, “Short sleep duration does not seem substantially to affect total energy expenditure, not is there sufficient evidence in support of any meaningful effect of restricted sleep on the different components of energy expenditure.”[2] Ultimately, there is a dual effect to the way in which a sleep deprived brain reacts to junk food. Walker further explains that one of the biological basis for this reaction in our brain function could be due to the buildup of adenosine, which would then hinders communication between networks in our brain.
Another explanation of the relationship stems from the balance between two hormones, Leptin and Ghrelin, which act on the nuclei of the hypothalamus to monitor energy and food intake. Leptin primarily inhibits appetite while Ghrelin, which is the released by the stomach, works to stimulate appetite. A Wisconsin Sleep Cohort Study reported that subjects who slept than 8 hours had BMI increase that was proportional to the reduction of their normal sleep lengths. Moreover, lower sleep durations were associated with low Leptin levels- 15.5% lower leptin for five hours of sleep instead of eight, and high Ghrelin levels- 14.9% higher ghrelin for five hours of sleep instead of eight. The imbalance between these hormones, which are part of the Orexin system that integrates control of feeding, wakefulness, and energy expenditure may explain the change in hunger, with increased appetite for snacks, fats, and carbohydrates, ultimately leading to weight gain.”[3] Sleep deprivation disturbs this balance, thus disturbing the balance of energy intake and energy expenditure.
Metabolism
Metabolism involves two biochemical processes that occur in living organisms. The first is anabolism, which refers to the buildup of molecules. The second is catabolism, the breakdown of molecules. These two processes work to regulate the amount of energy the body uses to maintain itself. During non-REM sleep, metabolic rate and brain temperature are lowered to deal with damages that may have occurred during time of wakefulness.
Sleep is important in regulating metabolism. Mammalian sleep can be sub-divided into two distinct phases - REM (rapid eye movement) and non-REM (NREM) sleep. In humans, NREM sleep has four stages, where the third and fourth stages are considered slow-wave sleep (SWS). SWS is considered deep sleep, when metabolism is least active. In normal metabolic function, the pancreas releases insulin after blood glucose levels raise. Insulin signals muscle and fat cells to absorb glucose from food. As a result, blood glucose levels return to normal.
Sleep loss can affect the basic metabolic functions of storing carbohydrates and regulating hormones. Reduction of sleep from eight hours to four hours produces 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 young men slept for the normal 8 hours. The next 6 nights, they slept for 4 hours. The next 7 nights, they spent 12 hours in bed. They all had the same diet. They found that there were changes in glucose metabolism that resemble that of type 2 diabetes patients. When the participants were tested after sleep deprivation, they took 40% longer than normal to regulate blood sugar levels after a high-carbohydrate meals. The secretion of insulin and the body's response to insulin decrease by 30%. Sleep deprivation also alters the productions of hormones, lowering the secretion of thyroid stimulating hormone and increasing blood levels of cortisol.
Can Sleeping More promote Weight Loss?
A regular sleep schedule can be a vital piece to increasing weight loss. While it is important to sleep more than an average of 6.5 hours per night, sleeping over 8.5 hours per night has been shown to contribute negatively to weight loss. Getting adequate sleep can also help account for any excess snacking that occurs throughout the course of the day due to feeling lethargic.
According to a recent study at Brigham Young University, a regular sleep schedule can make an almost immediate difference on the body’s ability to metabolize fat cells. In this specific study design, 300 college aged women (19–26 years old) were followed for a week and given an activity tracker which not only monitored movements, but also sleep patterns. The study also found that participants with lower BMI had higher quality of sleep, while those with higher BMI’s had lower quality of sleep. But was the reverse relationship also true?
While health professionals almost unanimously agree that if an individual is already getting 8 hours of sleep, then another half hour won’t make them lose weight; however, in cases where a person is used to getting 5 hours of sleep per night and they start getting 7–8 hours, it is common to see them start to shed pounds, especially in obese individuals. What causes this phenomenon? Two hormones, ghrelin and leptin, closely associated with appetite are key in the sleep and weight relationship. Ghrelin is the hormone that controls appetite and tells the body when to eat, and when one is sleep-deprived, they have more ghrelin. Leptin on the other hand, is the hormone that tells one to stop eating, and when an individuals is sleep deprived, they have less leptin. In order to keep these hormone levels in balance, a person needs to get adequate sleep so they do not feel the need to excessively eat in an effort to gain energy and reduce fatigue.
Effect of Oversleeping
There have been many connections made between oversleeping and certain disorders. Many of these have been made without any identifiable reason for correlation, and are mainly observational. WebMD reports that sleep apnea may cause oversleeping because of disruptions in the normal sleep cycle, that individuals who sleep more may be more prone to headaches because of neurotransmitters imbalances, back pain can increase with oversleeping because a certain level of physical activity is not being maintained, and that oversleeping may be correlated with depression and higher death rates.
However, these connections have not been subject to rigorous examination. On the other hand, there have been studies that have looked into the potential physical side effects of oversleeping on weight and weight – related conditions. One study at Université Laval's Faculty of Medicine in Quebec studied the life habits of 276 subjects over a 6-year period and found that about 20% of those with long (9+ hours) of sleeping time developed type 2 diabetes or impaired glucose tolerance as compared to 7% in those that slept an average amount of time. A further look into the 6-year Quebec Family Study demonstrates that long-duration sleepers (9–10 hours) were 25% more likely to experience a 5-kg weight gain, and a 21% increase in risk of obesity, when adjusted for age, sex, and baseline BMI, as compared to average duration sleepers (7–8 hours) (NCBI). Even when the researchers adjusted for energy expenditure and physical activity levels (among other covariates), these relationships remained significant. The researcher’s results indicate a U-shaped relationship between hours of sleep and type 2 diabetes, coronary heart disease and weight, but the metabolic mechanisms affected by long sleep duration are less clear than with sleep restriction and remain somewhat speculative.
A Nurses’ Health Study analyzed a group of about 72,000 US women who did not report having coronary heart disease at the onset of the study, and assessed the relationship between their reported sleep durations and incidence of a CHD event over a period of 10 years (JAMA). At the conclusion of the study, the data indicated that women who slept a longer duration (9–11 hours) were 38% more likely to have CHD than women who slept 8 hours. However, the researchers had no plausible explanation for a cause-and-effect relationship
Obesity Related Sleep Disorders
Sleep apnea
Sleep apnea is a sleep disorder which causes an individual to have short pauses in breathing or very shallow breaths while sleeping. These pauses in breathing can often cause the individual to wake up, snore, choke, or just generally disrupt their sleep. As a result, sufferers of the disease do not get quality sleep during the night and are tired during the daytime. Sleep apnea is very difficult to diagnose because doctors can’t exactly tell if a person has sleep apnea in a regular routine visit. Additionally the patient himself may not even realize he has sleep apnea because it occurs during sleep, so a partner or roommate is usually the first to notice symptoms. There are two types of sleep apnea, obstructive and central. Obstructive sleep apnea is more common among overweight patients, and occurs when the airway is fully or partially blocked at times during sleep. Any air that does sneak by the blocked passage can cause loud snoring. The second type of sleep apnea, central sleep apnea, is much more rare and has to do with the part of the brain that regulates breathing. The signal from the brain to the lungs is disrupted, resulting in pauses in breathing. Treating obstructive sleep apnea is much easier than central sleep apnea, and the treatment plan may include things such as lifestyle changes, mouthpieces, surgery, and breathing devices
Sleep in the Media
As obesity has become an issue of nationwide focus, all forms of media have begun to explore and report on the link between sleep and weight. The coverage spans from articles in Women’s Health Magazine on “6 Ways Sleep Can Help you Lose Weight,” to NPR’s story on the research linking a lack of sleep to obesity, to Harvard School of Public Health’s discussion of sleep as an “obesity prevention source” on their site. No matter how diverse the range of broadcasting, media sources seem to agree that, for whatever reasons, sleep is an important part of maintaining a healthy weight, and could be an effective approach to the obesity epidemic.