Sleep Disorders Health Center

Research has shown that bizarre and fantastic dreams are rare. You're more likely to dream about ordinary events or concerns you have when you are awake. Nightmares also reflect daytime concerns and often involve being trapped, alone, or in danger. Dreams may help you process memories and information – even if you don't remember them.

Like most other adults, seniors usually need about seven to nine hours of sleep, though they may have a harder time getting it in a single block of time. But healthy older people are less affected by sleep deprivation than younger people. In one 2009 study, healthy people aged 65 to 76 had faster reaction times, focused better, and dozed off less than people 18 to 29 years old when they went 26 hours without sleep. Whatever your age, lack of sleep -- even one night -- can cause you to be irritable and vulnerable to stress. It can affect your memory and your judgment, too.

Sleep needs are individual. Some adults need as few as five hours a night, some need a full 10, most require between 7 1/2 and 8 1/2 hours per night. But if you're sleepy during the day, you're likely not getting enough. Routinely falling asleep within five minutes may be a sign of severe sleep deprivation (and possibly a sleep disorder). And caffeine and other stimulants can't overcome its effects.

Sunlight helps your body maintain its internal sleep wake cycle. Waking up with sunlight -- and getting some sunshine early in the day -- can actually help you sleep better at night.

In a 2010 poll, Americans commonly cited money worries, longer workdays, health problems, and medication as reasons why they were losing sleep -- and sometimes skipping or avoiding sex. Ignoring sleep problems can lead to health problems, so talk to your doctor if you have trouble falling or staying asleep a few nights a week. He may suggest lifestyle changes, medications, or sleep studies to find out the cause of your sleep problems.

Sleepwalking is more common in kids than adults. But it can involve very complex -- and sometimes dangerous -- behaviors. A sleepwalker may drive a car, climb out a window, move furniture, or eat and get back in bed – all without ever waking up. It's a good idea to tell your doctor if you sleepwalk. Sleepwalking appears to run in families, but it may happen if you're fatigued, stressed, or with alcohol use.

According to studies, driving while drowsy is similar to driving with a blood-alcohol level of 0.08, the legal limit for intoxication in many states. And while alcohol slows your reflexes, driving drowsy may cause you to fall asleep, so you would have no reflex reactions at all. Shift workers and 16- to 29-year-old men are among those at highest risk for drowsy-driving crashes. If you can't stop yawning or are drifting from lane to lane, pull over for a 20-minute nap.

Errors in judgment caused by sleep deprivation played a big part in these and other disasters. But experts say they are high-profile examples of a growing problem: the consequences of cutting back on sleep. Losing sleep – whether for one or several nights – hurts concentration, working memory, reasoning, and judgment.

A catnap of 10 to 20 minutes may boost performance and alertness without making you groggy or interfering with nighttime sleep. But a snooze of a half-hour or longer can cause "sleep inertia" -- that feeling of grogginess and disorientation when you wake up from a deeper sleep. For most people, a good naptime is early afternoon, when your energy dips after lunch.

Several studies have shown that chronic sleep loss increases risk for obesity -- partly by unbalancing the hormones that trigger appetite and tell you when you've eaten enough. A 2012 study of more than 1,000 sets of twins showed that the opposite may also be true: People who get more than nine hours of shuteye tend to weigh less and have more control over their weight.

Your body rests, but your brain stays active. You drift between two sleep states -- REM (rapid eye movement) and non-REM. During deeper REM sleep, your brain activity increases. Researchers believe that both states are needed to reinforce memories and learning.

If you have trouble sleeping, experts advise banning electronics -- cell phones, TVs, computers -- from bed. The idea is to associate your bed with sleeping and sex. If you can't sleep or you wake up and can't go back to sleep, go into another room and do something relaxing, like reading or listening to music until you are sleepy. Go back to bed only when you are tired.

Studies show that the best temperature for sleep (if you're wearing pajamas) is a nippy 60 to 66 degrees Fahrenheit. This helps cool down your core body temperature, which brings on sleep. In fact, people with certain sleep problems tend to have a warmer core body temperature just before bed. If you do, try taking a cold shower before curling up in a cool room.