Do you take sleep for granted? Could it be that those days when everything seems to go wrong can be attributed to something as simple as not getting enough rest? How many times do you say, “I’ll catch up on my sleep on the weekend”? Do you ever feel like you just can’t get enough rest, or do you just lie there with your eyes open and wait for sleep?

Sleep…it’s a beautiful thing, but what do we really know about it?

With daylight savings time beginning this week (April 3), an opportunity to discuss the benefits and necessity of sleep is right on time. The National Sleep Foundation has designated this week National Sleep Awareness Week.

What is Sleep?

Sleep is a physical and mental resting state in which a person becomes relatively inactive and unaware of the environment.  In essence, sleep is a partial detachment from the world, where most external stimuli are blocked from the senses.

Why is Sleep Important?

Sleep is not a waste of time. It is a necessary and vital biological function. It is essential to a person’s physical and emotional well being. Without enough sleep, a person’s ability to perform even simple tasks declines dramatically.

The average sleep-deprived individual may experience impaired performance, irritability, lack of concentration and daytime drowsiness. They are less alert, inattentive and unable to concentrate effectively. Additionally, because sleep is linked to restorative processes in the immune system, sleep deprivation in a normal adult causes a biological response similar to the body fighting off an infection.

Persistent sleep deprivation can cause significant mood swings, erratic behavior, hallucinations and, in the most extreme, yet rare cases, death. The jury is still out on the long-term effects of sleep deprivation on health. Current research in this area is examining the effects of sleep deprivation on the immune system.

How Much Sleep Do We Need?

Six to eight hours a day is the average amount of sleep a person needs. That’s about one-third of a lifetime! As a population, we sleep about one to one-and-a-half hours less than we did 100 years ago.

Sleep requirements vary from person to person. Some people are naturally short or long sleepers. Thomas Edison, Martha Stewart and Jay Leno have remarked that they sleep less than five hours a night. In contrast, Albert Einstein and Calvin Coolidge claimed they needed ten or more hours per night. Other well known people such as Ronald Reagan and Winston Churchill took naps throughout the day.

Some experts suggest that the best way to determine personal sleep requirements is by waking up without an alarm clock. The amount of time spent sleeping would be the personal requirement. Other experts suggest that an ideal amount of sleep is the amount needed to feel refreshed and well rested in the morning and alert all day.

What is the Sleep Cycle?

A major reason why humans sleep is due to circadian rhythms, also known as the biological clock. At dusk, light sensors in our eyes stimulate certain physiological functions such as a drop in blood pressure and the secretion of the hormone melatonin. These reactions cause us to slow down and prepare for sleep.

Throughout the eight-hour sleep cycle, a normal adult alternates between two very different states, non-REM and REM (Rapid Eye Movement) sleep. Non-REM and REM sleep alternate in 90- to 110-minute cycles. A normal sleep pattern has 4-5 cycles. The cycle repeats itself throughout the night, much like a roller coaster.

Non-REM sleep consists of four stages that range from light dozing to deep sleep. Throughout this state of sleep, muscle activity remains functional, breathing is low and brain activity is minimal. Approximately 75 percent of the sleep cycle is spent in non-REM sleep. Simple thought processes may be reported if a person is awakened in any stage of non-REM sleep; however, he or she will not usually recall any specific dream.

REM sleep is where most of the dreaming takes place. It is signified by periodic eyelid fluttering, muscle paralysis, and irregular breathing. REM sleep is also called “paradoxical” sleep because brain wave activity is similar to an awakened state. It is during REM sleep that the brain blocks signals to the muscles to remain immobile so dreams will not be acted out. Adults spend 20-25 percent of their sleep cycle in REM sleep.

Sleep Disorders

At least 40 million Americans suffer from chronic, long-term sleep disorderseach year, and an additional 20 million experience occasional sleeping problems. These disorders and the resulting sleep deprivation interfere with work, driving and social activities. They also account for an estimated $16 billion in medical costs each year, while the indirect costs due to lost productivity and other factors are probably much greater.

The Future

Sleep research is expanding and attracting more and more attention from scientists. Researchers now know that sleep is an active and dynamic state that greatly influences our waking hours, and they realize that we must understand sleep to fully understand the brain. Innovative techniques, such as brain imaging, can now help researchers understand how different brain regions function during sleep and how different activities and disorders affect sleep.

Understanding the factors that affect sleep in health and disease also may lead to revolutionary new therapies for sleep disorders and ways of overcoming jet lag and the problems associated with shift work. We can expect these and many other benefits from research that will allow us to truly understand sleep’s impact on our lives.