Hormones and Sleep Patterns
A poll by the National Sleep Foundation found a steady decline in the number of hours Americans sleep each night. In 1975, the average American slept 7.5 hours, down from 9 hours in 1910. Today, adults sleep about 7 hours a night. Perhaps the importance of hormones and sleep patterns has been overlooked.
Cortisol, growth hormones and sleep patterns
As the human body ages, the changes in sleep patterns appear to trigger shifts in the endocrine system, altering hormone levels and metabolism. In fact, studies have been conducted to show that sleep may act as a form of hormone modulation therapy. In one study, 149 men aged between 16 to 83 were questioned about their sleeping habits, and the researchers found that hormonal change is associated with age-related changes in sleep quality. As the body gets less sleep, the cortisol levels will increase while Growth Hormones (GH) decrease. Cortisol is an anti-stress hormone made by the adrenal glands. Its production is increased with stress and the aging process. A high cortisol level is associated with mental and metabolic problems like memory loss and insulin resistance. Likewise a decrease in GH spells bad news as GH deficiency is linked to reduced muscle mass and strength, increased fat tissue and a weakened immune system, among others.
Reduced sleep is therefore associated with an increase of pro-aging hormone cortisol and reduction of anti-aging growth hormone. You get the worse of both worlds with hormones and sleep patterns.
Researchers study the quality of sleep is measured by looking at several parameters- the amount of time spent in the various stages of sleep – light sleep, deep slow wave sleep and REM sleep. The following observations can be made:
- As the amount of time spent in deep wave slow sleep decreased from 18.9% for ages 16-25 years to 3.4% for ages 36-50 years, this lost sleep was replaced by lighter sleep (stages 1 and 2). At this point of time though, there are no other significant changes to the bodies’ mechanisms.
- The transition from mid-life to late life (age 71-83 years) involved no further significant decrease in deep slow wave sleep but an increase in time awake of 28 minutes per decade at the expense of decreases in both light non-REM (rapid eye movement) sleep and REM sleep.
A chronic lack of sleep may cause far more serious problems than a tendency to nap off the next day. People who do not get enough sleep on a regular basis may become less sensitive to insulin which, over time, can raise the risk of obesity, high blood pressure and diabetes. Dr. Eve Cauter from the University of Chicago has noted that sleep deprivation in the long run can have the same effect on insulin resistance as aging. Therefore, people who get less than 6.5 hours of sleep per night are more susceptible to type 2 diabetes. Sleep loss is perhaps as much a risk factor as poor diet, sedentary lifestyle, chronic stress and aging.
Type 2 diabetes occurs when the body loses its ability to respond to insulin, the body’s key blood sugar-regulating hormone. This insulin resistance causes blood sugar levels to rise, which in turn can increase the risk for a number of serious medical complications including kidney damage, heart disease, blindness and lower limb amputations.
Researchers were able to show that healthy adults who got an average of 316 minutes, or 5 hours and 16 minutes, of sleep per night, over the course of 8 consecutive nights, secreted 50% more insulin than those who got 477 minutes, or about 8 hours of sleep every night. In other words, a 50% increase in insulin secretion is associated with a 30% reduction of sleep.
Irregular sleep patterns, such as that experienced by air stewardess, have also been associated with increase incidence of breast cancer as well. This may be due to the reduced melatonin level in those whose sleep cycle is frequently disturbed. These connections between hormones and sleep patterns that are shifting suggest that maintaining sleep quality throughout life is critical for optimum hormonal health.
Getting a good night’s sleep is essential for anti-aging and optimum hormonal modulation.
Sub-optimum sleep is associated with the following hormonal change:>
- Increase of the aging hormone called cortisol.
- Reduction of the anti-aging hormone called growth hormone.
- Higher incidence of adult onset diabetes.
- Reduction of melatonin secretion and higher incidence of breast cancer.
The solution is simple – sleep at least 8 hours a day, and sleep in total darkness to optimize melatonin production. Even a small amount of light can reduce melatonin production. Light nights should be switched off, and curtains drawn, if possible.
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