> Emotional and Mental Health > Energy and Fatigue

The alarm buzzes. A hand emerges from a heap of blankets to slap blindly at the sound–again and again. Finally, you rouse yourself to squint at the dial. With a groan, you realize you’ve slept in for the second time this week. What’s worse, you’re still tired. Sound familiar? If so, chances are you’re not getting enough shut-eye.

Sleep is a fundamental need shared by more than six billion people. We spend about one-third of our lives sleeping. It takes a healthy sleeper about 10 minutes to fall into the first of four stages of sleep. Stages one and two are lighter periods during which we’re more likely to wake up. Stages three and four are deep sleep, or delta sleep, during which our breathing and heartbeat continue to slow and our muscles relax. Rapid eye movement (REM) is another form of sleep that can randomly occur during the night. During this phase our brains are active, our heartbeat and breathing are quicker and we’re likely to have vivid dreams. Many studies suggest that good REM sleep enhances memory, although it isn’t conclusively proven yet. Nevertheless, we already have enough reasons to add “get enough sleep” to our “To Do” list.

In Support of Shut-Eye

When we sleep, our cells regenerate. The skin eliminates waste and the body circulates nutrients and hormones. There’s a reason Grandma recommended bed rest for a cold: that’s when the body’s immunity strengthens, infection-fighters form and strength is conserved to battle unwanted invaders.

A good night’s rest promotes faster recovery from injury and illness, increases brain function and reduces stress. A study last January in the Archives of Internal Medicine confirmed that too little sleep might raise the risk of heart disease. Of about 72,000 nurses, those with five or less hours a night were 39 per cent more likely to develop heart disease than eight-hour sleepers. Similarly, nurses getting six hours nightly were 18 per cent more likely to develop blocked arteries.

Lack of sleep causes irritability and inability to concentrate. Sleeplessness is also a major contributor to absenteeism, work inefficiency and car accidents. This is because many of us have disturbed sleep patterns or don’t get enough. Yet our bodies were biologically built to rest.

Our Circadian Clock

Our bodies are programmed to know when to hit the sheets. Fading daylight hits the retinas in the eyes, which triggers a message to a bundle of nerve cells in the brain called suprachiasmatic nucleus, or circadian clock. From there, more messages are sent to the rest of the body, telling it to prepare for rest. Our circadian clock is located in the hypothalamus part of the brain, which is also responsible for melatonin production. Melatonin is a hormone that lowers body temperature, causing increased drowsiness.

As a species, we’re designed to sleep less in brighter months and more in winter. “It’s a hibernation response,” explains Dr. Peter Bennett, director of the Helios Clinic in Victoria, BC. “Kind of like bears.” Longer hours of darkness cause more melatonin production, which makes us tired. So if you’re otherwise healthy but notice you sleep more at this time of the year, that’s normal. On the other hand, many people are susceptible to seasonal affective disorder (SAD), a form of depression typified by irritation, fatigue, weight gain and moodiness–definitely not desirable. In this case, various light therapy treatments–getting outside an extra half-hour each day or using special light therapy boxes–have been shown in numerous studies to be effective at reducing symptoms.

How Much Sleep Should We Get?

Everybody’s needs are different. Babies sleep for up to 18 hours a day. Some people get by on six. Most people need from eight to 10. As we age, we tend to require less, although it’s a very individual thing. It also depends on sleep quality. Getting up five times a night isn’t great; sleeping all the way through is.

Source: alive #248, June 2003