source: CBS news website, article dated 10/30/02 (CBS) Many Americans suffer from a serious lack of sleep, with more than two out of three getting less sleep than their bodies need. On The Early Show Wednesday, Dr. Neil Kavey, the director of the Sleep Disorders Center at Columbia-Presbyterian Medical Center, outlines the risks of sleep deprivation. Lack of sleep can cause psychological difficulties with emotions and cognitive abilities, he says. More research is showing sleep deprivation can cause physical setbacks by interfering with thyroid function, insulin sensitivity and glucose metabolism and causing secretion of the stress hormone, cortisol. When we don't get enough sleep, we're less alert and attentive, more inclined to be irritable and experience other mood problems. Concentration and judgment suffer and our ability to perform tasks decreases — increasing risk for accidents. Chronic sleep deprivation can easily lead to reduced quality of life and ill health. According to a Gallup Poll conducted for the National Sleep Foundation, Kavey says, one f every two people suffers from sleeplessness at some point in their lives, many of them chronically. In addition, modern life offers a lot of choices for using nighttime hours for daytime activities. Americans have reduced the average time asleep by 20 percent in the last century and added a month to our average annual work-commute time over the last 25 years. We need different amounts of sleep throughout our lifespan. Infants need 11 or 12 hours a night, and children and adults need eight or nine hours a night. Adolescents need as much sleep as younger children. This is an especially important area of concern because for many teens, social and school demands don't allow enough time for sleep. The American Academy of Sleep Medicine is trying to make sure that doctors, parents and teens understand that teens should get at least 7.5 hours of sleep per night. The risks to teens are potentially greater than for other groups when it comes to learning, mood, attitude and attention changes. Kavey says it's a myth that our need for sleep declines in later years. Aging itself takes a toll on the ability to get sleep. It's not that we need less sleep, we just tend to get less sleep because sleep problems are more common among the elderly. It used to be thought that insomnia was caused solely by psychological factors like anxiety or depression, but new research shows that it's neuro-physiological process that some people are inherently good at and some are not. Strategies can therefore be learned to maximize an individual's ability to fall asleep. It's important to realize that if you're not sleeping well, it could be something other than a psychological distraction and a doctor may be able to help you physically. How many hours of sleep time you get is not as important as how good you feel and how well you're able to perform the next day. Sleep starts with Stage 1, a light sleep, where muscles relax and brain waves are irregular and rapid. Stage 2 is characterized with larger brain waves and bursts of electrical activity. Deep sleep happens in Stages 3 and 4, when the brain waves are large and slow. Eventually you shift into a highly active stage characterized by rapid eye movements, or REM. This is when dreams occur, and the phase occurs several times per night. Brain waves appear almost the same as if you were awake. REM periods tend to become longer and more plentiful as the night wears on, accounting for about a quarter of total sleep. Sleep patterns change as we age. Newborns and children spend more time in deep sleep than adults. As we grow older, sleep tends to become more fragmented and we spend more time in the lighter stages. Sleep patterns are regulated by an internal biological clock in the brain. Most people's clock runs on a cycle of about 24 hours. Almost everyone's clock is set for sleep at night, especially in the early morning hours between midnight and dawn. We also get sleepy in the middle of the day, between about 1 p.m. and 4 p.m. When our lives clash with our biological clocks, sleep problems are inevitable. Twenty percent of American employees work non-traditional schedules and lack of sleep is a common problem for them. Shiftworkers who need to sleep when their clocks are set for wakefulness are most at risk for sleeping problems. Maintaining a rigorously regular schedule for both sleeping and waking activities can help the body to adapt. There's increasing evidence that a 15-20 minute nap during the day can improve alertness, sharpen memory and generally reduce the symptoms of fatigue. There is also an approved drug called Provigil that can increase alertness for people who suffer from daytime sleepiness. Other sleep aids and strategies can help you get the sleep you're missing in the first place. However, Provigil and napping are not substitutes for a full night's sleep.