With all the physical changes that occur as we grow older, it’s tempting to chalk up all our infirmities to the effects of aging.

But that’s a mistake. In some cases, physical changes that appear to be a normal part of aging signal the onset of a treatable condition. To protect yourself—and feel as good as possible!—it’s crucial to know what’s normal and what’s not as we grow older. For example…

STOOPED POSTURE

The vertebrae in the spine are separated by intervertebral discs, which act like shock absorbers. It’s normal for the discs to dehydrate and flatten with age. This is why the average person loses about half an inch in height every decade after about age 40. The same changes can alter the curve of the spine and cause a slight stoop.

What isn’t normal: Extreme curvature of the upper spine. In general, aging should cause no more than a 20-degree curvature of the spine. An extreme curvature is typically due to a condition known as “dowager’s hump” (kyphosis), which is usually caused by osteoporosis. Weak bones in the spine eventually crumble, changing the alignment of the spine and causing a stooped posture. Osteoporosis that has advanced this far can’t be reversed.

That’s why prevention is critical. Perform weight-bearing exercises, preferably before the bones have weakened. Walking and even dancing promote the development of new bone and protect your posture later in life. Weight-bearing exercise also can help even after bones are weakened—just be sure not to overdo it since you don’t want to cause more damage. Depending on the condition of your bones, you may need to switch to non–weight-bearing exercise, such as swimming.

Important: Make sure you’re getting enough vitamin D. Depending on where you live, it’s possible to get more than 90% of the vitamin D that you need just from sun exposure—the rest can come from D-fortified foods and/or supplements. Vitamin D enables the movement of calcium from the bloodstream into the bones. Ask a doctor for a blood test to check your vitamin D level. If it’s low, he/she can suggest the best ways for you to get more of this crucial vitamin.

PAIN

We all notice more aches and pains as we get older, often due to back problems, arthritis or other common conditions. These aches are normal if they are occasional.

What isn’t normal: Pain that’s severe or chronic. Good rule of thumb: See a doctor if you have severe pain and don’t know why—or if chronic pain interferes with your ability to live a normal life.

Important: Consider your mental health as well as your physical health. Pain and depression frequently go together—they actually share some of the same biochemical pathways.

That’s why drugs called tricyclic antidepressants, such as imipramine (Tofranil), are sometimes used to relieve chronic pain—even in patients who aren’t depressed. When pain is due to a physical problem, such as arthritis, depression also is common.

Get help right away, either from a doctor or a mental health professional (or both). Otherwise, you could be setting yourself up for a difficult cycle—ongoing pain increases depression, and the more depressed you are, the more pain you’ll experience.

Helpful: I strongly advise pain patients to do some kind of exercise, even if it’s just gentle stretches. Exercise increases endorphins, the body’s natural painkillers.

LESS SLEEP

After about age 50, most people tend to sleep less soundly, and they may sleep fewer total hours than younger people. The reasons for these differences in sleep habits are varied but may include more pain, medication use and nighttime urination in older adults.

What isn’t normal: Taking more than 10 to 15 minutes to fall asleep. See your doctor if you have trouble falling asleep more than, say, two nights a week. This delay in sleep onset might be due to stress. Or you could be having side effects from medications. Offenders include decongestants, beta-blockers and some asthma drugs. Don’t ignore sleep problems—over time, they can increase one’s risk for heart disease, diabetes and other serious conditions.

SLEEPWALKING

We still don’t know why people sleepwalk, but it’s been shown that sleepwalkers can engage in surprisingly complex activities, such as going to the refrigerator, then preparing—and consuming—a complete meal.

Sleepwalking is more common in children but also occurs in older adults. It’s usually not cause for concern unless you are putting yourself in dangerous situations, such as leaving the house or walking outside onto an unprotected balcony.

What isn’t normal: A condition known as sun-downing, which can mimic sleepwalking. With sun-downing, older adults sometimes are awake late at night and wander around the house. They’re partly conscious but confused and often combative. You can distinguish sun-downing from sleepwalking by the person’s degree of engagement. Sun-downers can interact with other people—sleepwalkers usually don’t.

If you suspect that you or a loved one may be suffering from sun-downing, see a doctor. It could be a sign of early-stage dementia. Sun-downing can also be a side effect (or wearing off) of medications, such as antidepressants, sleeping pills or antipsychotic drugs. In addition, it can be caused by narcotic painkillers, such as meperidine (Demerol). Once a physician changes the person’s medications—or adjusts the dosages—the nighttime wandering may stop.

BLURRED VISION

Do you have trouble reading small letters? Welcome to the over-50 club. The lenses of the eyes get less elastic with age, which impairs close vision, such as that required for reading. You can solve it with reading glasses or bifocals.

What isn’t normal: Consistently blurry vision. You could be developing “dry” macular degeneration, a leading cause of impaired vision. It occurs when cells in the macula (a structure in the center of the retina) start to deteriorate.

You might notice that words on a page are getting increasingly blurry. You also might have trouble adjusting to dim light. In addition, you’ll probably notice a general haziness and perhaps a blurred spot in the center of your vision.

Important: See a doctor immediately if you notice any of the above vision changes. Dry macular degeneration sometimes leads to the “wet” form, a leading cause of blindness.

Interesting: Although color blindness is usually present at birth in those who suffer from the condition, some people lose the ability to see certain colors later in life. For example, many adults age 50 and older have trouble distinguishing greens from blues. The lenses of the eyes, like tooth enamel, yellow with age. The yellow filters out these other colors. This problem is usually minor and requires no treatment.

LOSS OF LIBIDO

It’s common for men and women to experience gradual changes in their ability/desire to have sex. In men, there is a decrease in the frequency/strength of erections, often due to reduced blood flow. Women may have reduced lubrication after menopause because of declines in estrogen.

What isn’t normal: Significant changes in your desire for sex might be a problem. In general, physical factors, such as pain and/or lower levels of hormones, can cause a loss of libido. But you should consider your history when assessing desire for sex—a 50% or more reduction in frequency is worth discussing with your doctor. It is usually due to excessive stress—from money worries, relationship conflicts, etc.

Helpful: Stress-reducing practices, which can include regular exercise, making time for hobbies and/or practicing relaxation techniques, such as meditation.

Source: John Whyte, MD, MPH, an internist and chief medical expert and vice president, health and medical education, at the Discovery Channel. He has served as the medical adviser and director of the Council on Private Sector Initiatives to Improve the Safety, Security, and Quality of Healthcare. He is author of Is This Normal?: The Essential Guide to Middle Age and Beyond (Rodale). www.DiscoveryChannel.com