You don't need as much sleep as you used to.

It's not that you need less sleep, it's more like you may not be getting the kind of sleep you need to feel truly rested and refreshed.

Older adults need to get seven to nine hours of sleep per night, just like young adults. But older people have a tendency to have more trouble falling asleep and staying asleep than when they were younger, according to the National Sleep Foundation.

Research on the sleep habits of older Americans shows a general decline in REM or deep sleep and a rise in episodes of waking up during the night. Studies indicate physical and mental illnesses and the medications used for treatment can be reasons for many of the sleep disturbances. If you're having trouble sleeping, find out from your doctor what you can do about it.

In the meantime, try to stick to a regular schedule -- go to bed and get up at about the same time every day. Napping is good, but you may find yourself staying awake at night if you tend to nap during the late afternoon or early evening.

You have to give up running or jogging.

Unless years of hitting the pavement have damaged your knees and joints, you can keep on jogging or running to your heart's content.

"It's possible to continue to run until they plant you in the ground," says Scott Fisher, an exercise physiologist, director of the Fitness Center at Fairleigh Dickinson University in Teaneck, N.J., and an avid runner himself.

Yes, these are higher-impact activities, but you shouldn't have to quit, as long as you've been running or jogging in a way that's friendly to your body. Just don't think you're invincible.

"Listen to your body and take care of aches and pains before they become chronic injuries," says Fisher. "When you experience an ache or pain, modify your exercise regime and take time off to make sure you're appropriately recovered and your body has had an opportunity to heal itself up."

You may also want to adjust your running regimen as you get older.

"As people get older, they might find it more comfortable for them to, instead of running five or six days a week as they did in their 30s, to cut back and run three or four days and do cross training a couple of days, like swimming or cycling, which aren't as stressful on the joints," Fisher says.

Your menopause will be miserable.

Not necessarily, because every woman's menopause is unique. About 25 percent of women have no physical symptoms whatsoever. Many women experience mild to moderate side effects, while others experience more intense ones.

You're going to grow a hump.

No, you aren't, as long as your bones are strong. Spinal humps, caused by collapsing vertebrae, result from some cases of osteoporosis, the brittle bone disease. You can prevent the onset of osteoporosis by maintaining a diet rich in calcium and doing some weight-bearing exercises, such as walking or strength training, to build up your bone structure.

Sex and aging don't mix.

Yes, they do because humans are sexual beings all life long, not just during the young-and-buff stage. Part of enjoying good sex as you get older is to accept your body for what it's become. Educate yourself about some of the normal physiological changes that can happen with aging so you can be prepared to deal with them to have a fulfilling sex life. Here are some of those potential changes:

For men, age 50 to 89: Erections may take longer and not be as full or as firm as before; erections can subside more rapidly after ejaculation; it could take longer before you can experience another erection or orgasm.

For women, age 51 to 78: More time may be needed to respond to sexual stimulation; lubrication takes longer than in younger women; the vagina is less able to stretch than in younger women; orgasms can be shorter and less intense than in earlier years.

It's too late to start an exercise program.

There's a growing body of evidence that shows exercise is just as important for the health and well-being of older people, including the elderly, as it is for younger people.

One large-scale study that followed more than 50,000 alumni from the University of Pennsylvania and Harvard College for 40 years found death rates fell in direct proportion to how many calories participants burned each week.

"Almost invariably, the more active they were, the longer they lived," writes John Robbins, who referenced the landmark College Study in his book, "Healthy at 100: How You Can -- at Any Age -- Dramatically Increase Your Life Span and Your Health Span" (Random House, $25.95).

Exercise can lower your blood pressure and your cholesterol, increase your endurance and even help you sleep better. You can start by working yourself up to a 30-minute brisk walk five days a week. But get a checkup from your doctor first to be sure there are no underlying medical issues you would need to seriously consider before embarking on a fitness regimen.

You say goodbye to your muscle strength.

This little statistic could send you running for the nearest dumbbell: Most adults lose about a half-pound of muscle per year after age 20, according to the American Council on Exercise. But you can reverse a significant amount of that loss by strength training, which everyone, at just about any age, can start doing. Of course, you need to check with your doctor first to ensure you'll be safe while exercising this way.

One study found that even nursing home residents as old as 98, many of them with chronic conditions, experienced significant increases in muscular strength after just a few months of strength training. One of the huge benefits of strength training is it builds muscle mass, which can transform your body into a more efficient fat-burning machine.

Weight gain is a definite.

Most women gain an average of 10 pounds around menopause, but midlife weight gain isn't inevitable for every woman, nor is it for men.

You women need to remember, however, that you really do have a harder time losing weight once you've crossed over into middle age. This is because of the natural drop in the metabolic rate that occurs in women in their mid-40s.

The best tack to take is to optimize your physical fitness while making sure you get plenty of top-notch nutrition. Shoot for exercising 40 to 60 minutes per day, enough to burn 300 to 400 calories per workout session.

You're going to need a hearing aid.

Not everyone, of course, experiences hearing loss as part of the aging process. About a third of Americans ages 65 to 74 have hearing problems and about half of those 85 and older have hearing loss.

But there have been a growing number of media reports and warnings issued by health experts during the past few years that nearly half of U.S. boomers are experiencing some degree of hearing loss and at a more rapid pace than previous generations. Once it occurs, hearing loss is irreversible.

But you can protect yourself from experiencing hearing loss by knowing that exposure to noise levels above 85 decibels for more than 15 minutes can result in loss of hearing. The average rock concert is 115 to 120 dB, according to the Ear Foundation. Other noises that usually register above 85 dB are from such sources as lawnmowers, vacuum cleaners, musical concerts (aside from rock events) and motorcycles.

Protect yourself by wearing earplugs, which you can buy at the drugstore, sporting goods store or have custom made by an audiologist. You can also wear ear muffs, which are available at hardware stores.