The Importance of Sleep

During sleep, a number of vitally important processes take place. These include a variety of physiological activities that support the immune system and keep us well. When we are sick, we tend to sleep more. This is nature’s way of making sure we recover quickly from whatever is ailing us. All those extra hours add up to increased immune activity and improved well being.

Although sleep researchers have known for a long time that sleep can help us regain health, only recently has it become apparent that sleep also plays a preventive role. Recently, scientists have linked a lack of sleep with a number of serious diseases, among them Type 2 (non insulin-dependent) diabetes, heart disease and breast cancer.

Before we take a look at these findings, let’s take a closer look at what happens when we sleep and, in particular, the role of melatonin or “sleep hormone.”

Melatonin and Sleep

As soon as the sun sets, the pineal gland - a pea-sized structure located at the base of the brain - begins to secrete melatonin. This hormone plays a number of important roles, but is best recognized for its role as an inducer of sleep.

Melatonin secretion peaks in the early hours of the morning, and slows down significantly as dawn approaches. Under the influence of melatonin, during sleep, the body begins to secrete other important hormones. These include include growth hormone - necessary for children to grow and for adults to maintain muscle mass; leptin which helps to regulate appetite and weight and, in the morning, cortisol which stimulates wakefulness and prepares us for the day ahead.

Melatonin is also a powerful antioxidant, helping to protect the cells from oxidative damage.

Unfortunately, very few of us actually sleep the optimal number of hours required to allow completion of all of the melatonin-influenced physiological processes that contribute to health and well being.

Significant amounts of melatonin are released only in complete darkness, when the retina of the eye is no longer able to detect light. Artificial lighting, including the light from a street lamp, a digital clock or alarm system, even the small amount that steals under the doorway from a hallway light, can all suppress secretion of melatonin. Electric lighting has made our days longer and our nights shorter, impacting nature’s inborn rhythms and, ultimately, our health. (Significantly, the natural light of the stars, moon and lightning do not inhibit melatonin secretion.)

Sleep and Women's Health

Although both men and women experience insomnia, more women are affected by inability to sleep than men. The problem is compounded by hormonal fluctuations before, during and after menopause.

As we age, calcium deposits affect the pineal gland. Some researchers believe that the resulting inhibition of melatonin secretion affects the sleep and overall health.

A recent study, reported in the British Journal of Cancer, suggests that women who are completely blind have an average 36 percent lower risk of developing breast cancer compared with sighted women. Women who became blind before age 65 appeared to be particularly protected against breast cancer, with cancer incidence rates as high as 49 percent below those of sighted women¹. Four later studies supported these findings, and another three studies showed increased breast cancer rates among women who were exposed to artificial light throughout the night, mainly shift workers².

Melatonin is known to suppress estrogen levels, and estrogen is known to be a causal factor in the development of breast cancer. The researchers speculate that, since blind women are in perpetual darkness, their elevated melatonin levels (and associated reduced estrogen levels), may exert a protective effect against breast cancer. In the case of female shift workers, exposure to artificial light during the time that melatonin levels should peak (between 1:00 and 2:00 a.m.), caused a reduction of melatonin released, and an associated increase in the level of estrogen.

While these studies suggest the increased importance of getting enough sleep, it is also important to recognize that research in this area is in its infancy.

Sleep and Diabetes

Type 2 diabetes develops when the body fails to respond properly to insulin - the hormone that regulates blood sugar. This failure to respond is known as insulin resistance. When levels of blood sugar are high, the cells are unable to use this sugar for energy. This, in turn, increases the risk of serious medical conditions including kidney damage, heart disease, and impaired vision.

Dr. Eve Van Cauter, an endocrinologist at the University of Chicago, found that chronic sleep deprivation (6.5 or fewer hours of sleep per night), had the same effect on insulin resistance as aging. In one study, Dr. Cauter took several men in their 20s, and allowed them to sleep for only four hours a night. After one week, the young men tested as "pre-diabetic" in glucose tolerance tests - at levels typical for men in their 60s. As soon as the subjects had caught up on their shut-eye, their insulin levels returned to normal.

Sleep and Heart Disease

According to recent research, women who are chronically sleep deprived appear to be at increased risk for heart disease.

In 1886, researchers assessed over 71,600 female health professionals aged 45 to 65 for for heart disease. All who entered the study were free from heart problems, and were questioned about their sleeping habits. The subjects were then followed for a period of ten years.

uring the course of the study, 934 heart problems were documented, both fatal and non-fatal. Women who slept five or fewer hours a day were 45 percent more likely to experience a heart problem than those who slept eight hours.³.

Curiously, when subjects slept for more than nine hours a night, the risk for heart disease increased by 38 percent. Study analysts note, however, that more than nine hours of sleep a night is unlikely to be a cause of heart disease. It is more likely that the women slept longer due to other health issues possibly associated with cardiovascular problems, such as stress-induced fatigue.

More study must be completed before doctors can say for sure that not getting enough sleep increases the risk of breast cancer, diabetes and heart disease in women. However, initial findings suggest this may be the case. One thing we know for sure is that long-term sleep deprivation (even by one hour a night), can make us feel tired, irritable, and unable to perform to our maximum capacity. This fact alone should encourage you to make going to bed earlier a lifetime habit.

1. Inverse association between breast cancer incidence and degree of visual impairment in Finland, British Journal of Cancer (1999) 80, pp. 1459-1460.

2. Schernhammer, E.S., et al. Rotating night shifts and risk of breast cancer in women participating in the Nurses' Health Study, Journal of the National Cancer Institute, Volume 93, 2001, Number 20, pp. 1563-1568.

3. Ayas, N.T., White, D.P, Manson, J.E., et al. A prospective study of sleep duration and coronary heart disease in women. Archives of Internal Medicine, 2003;163:205-209.

Can Sleep Help You Lose Weight?

Scientists know that melatonin affects appetite and satiety (the feeling of satisfaction that is the reverse of hunger).

When we sleep, melatonin encourages the body to secrete another hormone, called leptin. This hormone - named after the Greek word leptos, meaning “thin” - is an appetite suppressant that also increases the metabolic rate. One of leptin’s functions is to make sure we do not awaken at night due to hunger.

When we are deprived of sleep, low melatonin levels lead to low leptin levels, slowing down the metabolism of carbohydrates. This gives rise to high levels of blood sugar. Increased blood sugar levels lead, in turn, to increased output of insulin and an associated desire to consume more carbohydrates¹.

When insulin levels are high, the body receives the message to store unused energy as bodyfat. Since decreased melatonin output is also associated with fatigue, over time, these combined factors may lead to the inability to maintain an appropriate weight.

1. Spiegel, Karine, PhD., Leproult, Rachel, PhD., Van Cauter, Eve, PhD. Impact of Sleep Debt on Metabolic and Endocrine Function, The Lancet, 1999, Volume 354: p 1435.

Tips for a Healthful Sleep...

• Eliminate all light sources in your bedroom. The sleep hormone, melatonin, is only produced in complete darkness. If you cannot remove or eliminate light sources, wear a sleep mask or blindfold.
• Get to sleep as early as possible, preferably between 9:30 and 10:30 p.m. If you are not used to getting to bed this early, try moving your bedtime back by 30 minutes each week until you are in bed by 10:30 p.m.
• Try not to eat after-dinner snacks, such as bread or sweets. These cause the blood sugar to rise steeply, and then fall again a few hours later, triggering the hunger response. This is likely to wake you up.
• If you have trouble falling asleep, try having a warm bath before bed, and/or a warm non-caffeinated drink such as milk or herbal tea. Read something soothing, meditate, or listen to relaxing music.
• Don’t have a nightcap. Alcohol may make you feel drowsy, but its effect is short-lived. This means you will likely wake up a few hours later, unable to fall back to sleep.
• If sleep continues to elude you, consider taking a melatonin supplement such as Vivitas™ Melatonin, available from London Drugs.

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