Friday, October 26, 2007

How much sleep do we need?

A normal night’s sleep is most easily divided into two types: what is commonly called REM (rapid eye movement, or dream) sleep and non-REM (nondream) sleep. You can tell that a person is in REM sleep when the bulge of his eyeballs can be seen rapidly moving under his eyelids.

So, what happens when we are regularly deprived (voluntarily or involuntarily) of these repeated cycles, thus creating a sleep deb
t? If we get fewer consecutive hours of sleep than we need, we won’t get as much of the last and longest REM sleep period, which is vital to mental health. If our sleep patterns become irregular, consisting of a series of naps, we often don’t get to the deep delta sleep that is necessary to mend our bodies. Those in serious debt suffer from shortened attention spans, memory and vocabulary loss, a lessened ability to think analytically, and diminished creativity. What triggers the body to demand sleep? A number of factors evidently combine to create a circadian (daily) rhythm, or wake-sleep pattern. Brain chemistry appears to play a role. Also, there is a nucleus of nerve cells located in the brain that evidently helps control the sleep cycle. This “clock” is situated close to where the optic nerves come together. Light thus influences how sleepy we feel. Bright light wakes you up, while darkness induces sleep. Your body temperature is also involved. When your temperature is highest—typically midmorning and midevening—you are the most alert. As your body temperature drops, you become increasingly drowsy.

How much sleep do we need?
Scientists tell us that, on average, humans require about eight hours of rest per night. But studies also show that individual needs vary dramatically. An honest self-analysis can determine if you are already in a healthful pattern or are experiencing a sleep debt. Experts generally agree on these signs of healthy sleep: · Sleep comes easily without resorting to drugs or fighting restlessness or anxiety. · You are rarely aware of waking up in the middle of the night, but if you do wake up, you can go back to sleep quickly. · Waking up occurs naturally at approximately the same time each morning and usually without the aid of an alarm clock. · Once you are up and going, you feel awake and fairly alert all day.

Practical Points
What about those with occasional insomnia? Some experts suggest these practical steps:

1. Avoid alcohol as well as stimulants such as coffee or tea near bedtime. Many people mistakenly believe that alcoholic beverages will help put them to sleep. However, clinical studies show that alcohol can have a rebound effect and keep you awake.

2. Quit smoking. One authority notes: “Smokers have greater difficulty falling asleep, because cigarettes raise blood pressure, speed up the heart rate, and stimulate brain-wave activity. Smokers also tend to wake up more in the middle of the night, possibly because their body is experiencing withdrawal symptoms.”

3. Avoid extreme mental or physical stimulation just before bedtime. Exercise promotes proper rest but not if done immediately before trying to sleep. Tackling big problems or mental challenges just before you go to bed can interfere with the relaxed mood often needed to drift off to sleep.

4. Make sure that your bedroom is quiet, dark and, where possible, relatively cool. Regarding noise, consider one famous study of people living near an airport who claimed that they no longer heard the airplanes. When their sleep patterns were tested, their brain waves recorded each landing and takeoff! The researchers concluded that the test subjects averaged about one hour less of quality sleep each night than those in a quieter zone. Earplugs or other methods of reducing noise would have greatly assisted them in getting restful sleep. Some find that white noise (defined as any low-frequency, steady, and monotonous hum), such as made by an electric fan, is especially helpful if there is a need to mask street sounds.

5. Be cautious about taking sleep-inducing medications. There is growing evidence that many drugs prescribed to induce sleep are habit-forming, lessen in effectiveness with prolonged use, and have damaging side effects. At best, such drugs may be useful for short-term therapy. Since insomnia can be brought on by stress, it is thought that one key to healthy sleep is making the time just before going to bed a quiet, pleasant period. It may be helpful to set aside the cares of the day and do something enjoyable, such as reading.

Some Common Misconceptions
1. Drinking caffeinated beverages is the best way to stay alert on a long drive. Studies suggest that drivers often mislead themselves into thinking that they are more awake than they actually are. If you cannot avoid making a long, nighttime drive, it is better periodically to pull over in a safe area and take a short nap (from 15 to 30 minutes), followed by walking or jogging while stretching arm and leg muscles.

2. If I am having sleep problems, napping is the answer. Perhaps, but many experts believe that the ideal pattern is one long stretch of sleep every 24 hours. A short, midday nap (typically 15 to 30 minutes) may help restore alertness during the afternoon slump without throwing your longer sleep cycles out of rhythm. But napping within four hours of bedtime may be detrimental to healthy nocturnal rest.

3. The dreams we remember have robbed us of proper rest. Dreams (usually occurring during REM sleep) are a sign of healthful rest and typically happen four or more times during each normal night’s rest. Studies indicate that the dreams we remember are simply those from which we were awakened, either while they were happening or within a couple of minutes after they ended. On the other hand, a nightmare may create anxiety and make going back to sleep difficult.

Related post: Sleep debt and Sleep disorder

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