University of Iowa Health Science Relations and
Mark Dyken, MD
Associate Professor of Neurology
First Published: 2004
Last Revised: April 2004
Peer Review Status: Internally Peer Reviewed

What is sleep?

Webster defines it as the natural suspension of consciousness during which the body restores itself.

To be more precise, sleep is a biological function caused by the discharge of specific neurons in certain parts of the brain. It involves an alternate cycle of non-rapid eye movement (NREM) and rapid eye movement (REM). The cycle consists of approximately 90 minutes of NREM followed by REM. This 90-minute cycle is repeated three to six times during the night.

However you define it, sleep affects every human physiological and psychological process.

The mind and body do not shut down during sleep. Quite the contrary. Sleep permits the brain to consolidate the day's learning into memory and improves the brain's ability to learn repetitive skills, such as riding a bicycle. During sleep, the body does maintenance work--replacing old cells and re-energizing organs and muscles. The "work" sleep does for you at night is vital for you to function at your best during the day.

But society doesn't treat sleep with very much respect. This is a 24-hour society--shift workers, 24-hour stores, the Internet. You steal from your sleep hours to add extra hours for activities. The number of hours the average person sleeps has been reduced by 20 percent in the past century. Society has changed, but your body's need for sleep has not.

"We know sleep is necessary for the physical and mental," says Mark Dyken, MD, University of Iowa Health Care Sleep Disorders Center. "All organisms require some form of quiet state. If we don't give the body enough sleep, it will make sure that it gets what it needs. Truck drivers and shift workers have a difficult time getting enough sleep so they don't fall asleep at inappropriate times."

The body has its own daily rhythms or circadian cycles. "From approximately 1 to 3 a.m. and 1 to 3 p.m. is when most people tend to naturally want to sleep. The siesta falls into that rhythm," Dyken says.

What happens when you don't get the sleep you need? For one thing you get grumpy. Sleep deprivation also can lead to increased fatigue, poor attention and motivation spans, memory lapses, and poor judgment.

What is enough sleep? Dyken says it depends on the person.

A baby's biological rhythm is very different from an adult's. Just ask anyone who has raised a child. "They are a different animal," Dyken says. "Their sleep/awake patterns can be every three to four hours. That's why so many new parents wonder if their child will ever sleep through the night.

"Kids up to age 12 need about 11 hours of sleep each night. This will probably be some of the best sleep of your life," Dyken says. Older children and young adults through their 30s need seven to nine hours of sleep each night.

"At age 40, people begin to notice that their sleep patterns change. At age 50, major differences are recognizable," Dyken says. More than 50 percent of Americans aged 65 and older have a sleep problem. "Older people get less sleep. They don't necessarily need less sleep, but pain, medications, stress, and other health factors affect their sleep. It is part of the normal progression through life."

What about those occasional times when you can't fall asleep?

Dr. Dyken says there are two schools of thought on what to do.

If you haven't fallen asleep in 15 minutes, he suggests staying in bed. "Have a good relaxing book nearby and read until your eyes are ready to droop. For some people, it may be some other form of relaxation they can associate with the sleep initiation process. It is all part of positive conditioning," he says.

The other schools of thought suggest that after 15 to 30 minutes of not being able to fall asleep, especially if you are becoming anxious, you should get up, go to another room and read, engage in quiet activity, take a warm bath. Don't let yourself fall asleep in another room, but return to your bed when you feel drowsy.

"Sleep is an individual experience," Dyken says. "What helps one person sleep, may not help the next person." He says most people know themselves well, and after keeping track of some nighttime routines, can determine what does or does not lead to a good night's sleep. "If you have a cup of ginseng tea before you go to bed and that works for you, fine. It may not work for everyone," he says.

Conditioning, both positive and negative, has an impact on how people fall asleep and stay asleep.

"People can condition themselves to get ready for a good night's sleep by creating a psychologically inviting atmosphere in the bedroom," he says. The bedroom should be quiet, have a minimum of light and the temperature should be constant. The bedroom should be used for sleeping, not doing bills, planning your schedule for the week, or using your laptop to catch up on e-mails.

Negative conditioning can be a powerful influence on a person's sleep patterns. "What keeps us awake or wakes us up can be recurring, negative thoughts." Dyken says.

"If something is bothering you, you are depressed or have suffered a tragedy, these thoughts can interfere with your sleep, even when the problems or events are behind you," he said. Why? "Because it has become part of your sleep pattern. The pattern must be altered so you can return to a normal sleep routine."

Staying up later than normal for special events has its consequences, for adults as well as children.

Sleep loss that accumulates from one night to the next is called a "sleep debt" or sleep deprivation. Even a modest loss of sleep, like staying up to celebrate with friends, can produce a sleep debt when sustained over several nights.

While Dr. Dyken suggests you avoid naps if you have trouble sleeping at night, he indicated that napping was not always bad. "You can't really catch up on sleep, but it is better to take that afternoon weekend nap than to have missed the sleep completely.

"For every hour of sleep missed, it takes a young person approximatley 24 hours to adjust," he said. Jet lag is an example on a large scale. "If you travel to London, you will experience a seven-hour time difference and it will take you a full week to completely adjust."

According to the National Sleep Foundation, there is increasing evidence that a 15 to 20 minute nap can improve alertness, sharpen memory, and generally reduce the symptoms of fatigue.

A nap is not a substitute for a full night's sleep. It is only a short-term fix.

Top sleep disorders

Insomnia - not being able to fall asleep, the feeling of not having slept well or long enough.

According to a 1996 National Sleep Foundation survey, 49 percent of Americans suffer from insomnia and 75 percent of them list stress and depression as the reason. Dr. Dyken says insomnia is the number one reason people come to his Sleep Disorders Clinic.

Short-term insomnia, lasting no more than three weeks, may be caused by concerns about money or relationships, the death of a loved one, health problems, boredom, etc. Long-term insomnia may be attributed to heart disease, diabetes, asthma, and ulcers, to name a few. Chronic drug or alcohol abuse, as well as excessive use of caffeine and sleeping pills, can disrupt regular sleep patterns.

Primary Snoring - loud upper airway breathing sounds during sleep.

Snoring can sometimes be a symptom of a serious disorder. When an individual snores loud enough to disturb others, it is usually a strong indication of sleep apnea.

Suggestions:

• Avoid alcohol within two hours of bedtime. Alcohol depresses breathing and makes snoring more frequent.
• Avoid sleeping pills. They tend to depress breathing and make snoring worse.
• Lose weight.
• Take medications with care. Be aware of possible side effects.
• Sleep on your side, not on your back.
• Treat allergies or cold symptoms.

Restless Legs Syndrome (RLS) - uncomfortable tingling or prickling sensation of the legs during sleep.

If you have RLS, the prickling sensation is so uncomfortable that only massaging your legs or moving them will help. The discomfort can keep you awake and wake you up. The discomfort and sleeplessness that follow RLS can lead to serious psychological distress and depression.

There aren't any cures for RLS, but medications are available to treat it.

Sleep bruxism - grinding of teeth during sleep.

It occurs in 85 to 90 percent of adults and 50 percent of children. It leads to severe dental damage in five percent of the cases.

Sleepwalking - nocturnal walks the sleeper doesn't remember.

It occurs in adults but is most prevalent in children. Sleepwalkers don't remember their walks, but seem to navigate surprisingly well. It seems to be a temporary sleep mechanism malfunction that occurs during the deeper stages of sleep. It tends to run in families. Most leave sleepwalking behind at puberty.

Suggestions:

• There is no medical intervention.
• Keep habitual sleepwalkers safe from harm by keeping doors and windows closed and guarded.

Sleep talking - talking while asleep.

Sleep talking can range from a word or two of gibberish, to an entire speech. The sleeper generally has no memory of the event. It is harmless, temporary, and can be brought on by stress or illness.

Is sleep sometimes a problem?

Here are some suggestions to make getting a good night's sleep a little easier:

• Establish a regular time to go to bed and time to get up. Follow them consistently - even on weekends.
• Establish a sleep ritual. Do the same things each evening as you get ready for bed to cue your body to settle down for the night.
• Don't exercise within two hours of bedtime. Instead of wearing you out, it will raise your heart rate and boost adrenalin, making it difficult to sleep.
• Avoid alcohol three to four hours before bedtime. Alcohol may induce sleep for two to four hours, but after that can interrupt or disrupt sleep.
• Avoid stimulants like caffeine. They can interfere with falling asleep and may prevent deep sleep.
• Avoid smoking. Smokers take longer to fall asleep, awaken more often, and experience disrupted, fragmented sleep.
• A light snack may help you fall asleep, but a large, heavy meal will keep you awake, especially if you suffer from acid reflux.
• Unwind early in the evening. Try to deal with problems several hours before bedtime.