Consider the older man who slips into the bathroom before bedtime and surreptitiously swallows a Viagra pill. He decides against telling his wife, afraid she might think he's having a problem because he's no longer attracted to her.

Now picture an older woman admitting to her girlfriend that sex with her husband isn't what it used to be. She'd like to suggest he try Viagra but hasn't, afraid that he'll feel more inadequate than she suspects he already does.

A widely reported survey showed recently that older Americans live active sex lives. They are supported in this endeavor by an active pharmaceutical industry that reaps increasing profits from sales of sex-enhancing drugs. Viagra, used to treat erectile dysfunction, brought in $1.7 billion in 2006, for example; its rival Cialis, $971 million.

But no matter how many pills, shots and creams drug companies dispense, therapists say, they are far from finding the potion that will truly enhance the sex lives of an aging population: the ability to talk freely about sex, or the lack thereof. Mortgage payments, Iraq, even a sick child are easier to discuss than sex, especially for boomers who grew up thinking they could have all the sex they wanted, at any time, only to find that they no longer can.

When people are younger — in their 20s and 30s — the parts hum. But as bodies age, hormonal levels in both men and women change, sometimes not at the same time. One partner may be up for sex, the other not. A woman in her 40s, therapists say, frequently experiences an increase in desire while a man's performance in those years is taking a dive. At about 50, the average age for menopause, her desire may begin to decline and reach a level lower than his.

Add to this the routine of a marriage or long relationship, as opposed to the fireworks of new attraction, and you've got the setup for a long night's snooze every night.

"Most of us really care about our partners and want to be in those relationships," says Gina Ogden, a Cambridge, Mass., sex therapist. "But sexual pleasure after 20-plus years of being together? The blush is off the rose. And we don't have a language for talking about it. The experience is larger than you can count or measure."

BUILDING BONDS

Sexual satisfaction contributes to overall health, experts say. It may not be on par with, say, eating lots of fresh fruits and vegetables, but it's right up there. Couples who enjoy sex together fight less often and relax more easily. If they have children, family life runs more smoothly.

A good sex life "helps build the bond of family and makes up for things that wear and tear on the family," says David Scharff, a Washington psychiatrist and former president of the American Association of Sexuality Educators, Counselors and Therapists.

Carolyn Shaffer, a Bethesda, Md., psychologist, has seen this pattern among her clients as well, particularly men. "A man can have all these problems with his wife, but when we fix the sex life, the other things go away," she says.

That said, older Americans are enjoying sex in large numbers. A recent survey of Americans ages 57 to 85, which was headed by researchers at the University of Chicago and published in the New England Journal of Medicine, revealed that more than half were sexually active at least two or three times a month.

But almost half of the sexually active also said they had problems with sex.

No. 1 for men, according to the Chicago study, was erectile dysfunction, or ED. Most sexual problems have multiple possible causes, which is why they're difficult to talk about with any clarity, and ED is no exception. It can occur because of disease, excessive drinking, concerns about work or family.

"Is it that he can't or doesn't want to?" asks Scharff. "He may not know."

In the Chicago study, women reported more problems with sex than men, with almost half having experienced lack of desire.

For some, that may have been for physical reasons such as pain during intercourse. In that case, they may be quite happy simply spending a quiet evening together watching a movie.

"I don't have a lot of these women saying, 'I want my husband to take Viagra,' " Washington social worker Gwen Pearl says.

Emotional reasons, particularly if tied to their relationship with their partner, can also diminish the quality of sex for women.

Sex, Scharff says, is a true psychosomatic function for both sexes; if a woman is angry at her partner, that will show up in bed.

On the other hand, if she is happy with him, she may enjoy sex as much as, or more than, she would if she were receiving hormonal treatments, according to therapist Ogden.

"When you're having an amazing heart-to-heart connection, your oxytocin levels jump, your dopamine starts to pump, making you able to be sexual and enjoy being sexual," Ogden says.

This can hold true even if a partner is ill. Helen and Ronald, a Midwestern couple who asked that their last names not be used, learned how important conversation is when Helen developed breast cancer and had to have a breast removed.

"I just would not allow her to think herself into an asexual mode," Ronald recalls. "I knew that was not her nature. If I wasn't vigilant, she would say things like, 'Oh, my God, I am disfigured.' It was my job to say, 'What, you've noticed something I haven't?' "

For a while, says Helen, she had little desire for sex. "That was hard," she says. "I have a highly sexual nature." But Ronald had a soothing touch, a coaxing tone of voice and unlimited patience. "Those things really helped," Helen says.

Ronald says they also paid close attention to when certain techniques weren't working, "like the movie director who sees something he doesn't like and yells, 'Cut!' And then calls the cast together to talk."

THE RIGHT TIME

Ah, yes, back to talking.

Therapists say discussing sex is best pursued when both partners are relaxed — not in bed, or after they've just come home from work or taken out the garbage or finally gotten a fussy child to sleep. Sex merits caution because talking about it can raise anxiety levels that inhibit the very thing partners are hoping to achieve.

"You have to find a neutral time," Pearl says. "In essence, make an appointment. Say something like, 'I've been thinking about our sexual relationship and I'd like to talk about it. Would you be willing, and when is a good time?' "

Once couples agree on change, therapists advise them to vary what leads up to the lovemaking. Some couples enjoy watching a sexy movie, or reading erotica together, or taking a bath, according to Lawrence Sank, a psychologist who shares an office with Shaffer, his wife. "Routine predictability is the enemy," he notes. "Couples need to have novelty. And it need not be swinging from the chandeliers, or a third party."

Shaffer recommends her clients go on a weekly date, a picnic or long walk, anything that reminds them why they picked each other. She also suggests couples relax together each night, alone. If children are at home, she says, they can be told that Mom and Dad are off-duty.

The good news is that couples become more alike in their need for closeness in later years, with many men learning to enjoy the same pleasure of the touch that their partners have always prized.

"Couples don't realize what they have in each other," Shaffer says. "It's like a gold mine they're not mining."

Some couples have known that all along. A Baltimore woman tells the story of her parents who woke up one morning several years ago to a huge snowfall. She called to check on them and got her mother on the phone.

Mom, giggling, asked her daughter, "Do you know what your father just said? He looked outside and said, 'On a day like today you do three things: build a fire, pop popcorn and make love to your wife.' We could only do two," she added, "because we don't have a fireplace."

The couple asked that their names not be used. But we can tell you this: She was 85 at the time. He was 89.

Washington Post staff research-er Karl Evanzz contributed to this report.