"The average couple doesn't talk much -- about 15 minutes a day," he says, even though they may eat together or watch TV together. Some of the most significant talking takes place in the minutes before they fall asleep. And there's one other reason being able to sleep in the same room is good, he found. Many of the women he interviewed said they felt safer sharing a bed.
Snoring is by far the biggest reason people resort to separate bedrooms, as the National Sleep Foundation's poll illustrates -- with sleep apnea, insomnia and leg twitching (Restless Legs Syndrome) also in the mix.
The problem is so pervasive that CNN.com reports a new home trend: Some master bedroom suites in upscale houses are being equipped with small "snoring rooms."
"The snorer is quite happy with the situation," says Penny Olivi, 49, with a laugh. "It's the other person who isn't." Olivi, who lives in New Freedom, Pa., and commutes to Baltimore, usually tries to change her husband's position to stop his snoring. "Sometimes I wake him up, and he goes down to sleep on the sofa. He's a wonderful person."
"When you're young with kids you don't get any rest," she says ruefully, "and then you age and one of you starts snoring and you don't get any rest."
Age and weight gain are often contributing factors to snoring. Rosenblatt found in his interviews that sometimes just a few pounds could make a difference. One person told him that if he went from 220 pounds to 222 pounds he would start to snore.
The first thing to do if you share a bed with someone who snores loudly is to make sure it isn't caused by a serious medical condition like sleep apnea. If it's not a medical disorder but a nuisance, sleep experts recommend a variety of remedies, ranging from the logical to the ridiculous -- starting with persuading your bed partner to lose weight if he or she needs to.
If the snoring isn't too loud, you can try going to bed first so you're asleep when the snoring starts.
That's what Lisa Rotellini, who lives in downtown Baltimore, does. She's slept with foam earplugs every night since she got married nine years ago, "although they're uncomfortable and my ears are getting sensitive. Even with earplugs he'll sometimes wake me up snoring. It's getting louder and louder, but it's not fair to wake him up. It's not his fault. I'll sleep six or eight hours, but it's not restful anymore."
"It's difficult for me to fall asleep anyway," Rotellini, 32, says. "As long as I can remember, sleeping has not come naturally to me. With his snoring there's an added anxiety."
Besides falling asleep before your bedroom companion does or using high-quality earplugs, you can try a fan or a white-noise machine that produces a constant background hum, or a nasal spray for a sinus condition, suggests Dr. Nancy Collop, a Johns Hopkins pulmonologist whose outpatient practice deals almost exclusively with sleep disorders.
"The worst snoring is usually when the person is on the back," she says, "so you can always use what we call 'elbow therapy.'" A quick jab is sometimes all it takes.
One doctor she knows tells his patients to wear a bra backward and put tennis balls in it to keep them off their backs. "But most men won't want to do that," she says with a laugh.
If your bedroom companion keeps you awake because he or she is a restless sleeper, Collop recommends separate beds in the same bedroom.
"Separate bedrooms," she says, "should be a last resort."
Half the population has insomnia at one time or another, says Greater Baltimore Medical Center's Dr. Brian Bohner. If you have trouble falling or staying asleep, your bed partner is probably sleep-deprived, too. Here are some suggestions for getting a better night's rest:
The one "cure" that Bohner says he stresses most is physical exercise.
Use the bed only for sex and sleep; don't read or watch TV there.
Shift workers who have insomnia can benefit from light therapy. They should keep the blinds tightly shut when they're trying to sleep and wear sunglasses during the day.
If insomnia is a problem, don't be a clock watcher, says Johns Hopkins' Dr. Nancy Collop. Turn the face of the clock away from the bed.
Set a regular sleep schedule. Getting to bed at the same time each night is especially important.
If you don't fall asleep after 10 minutes or so, says Collop, get out of bed and do something soothing like reading or crocheting in a low light.
Don't sit in front of a computer screen if you can't sleep. The light it emits is stimulating, Collop says.
Bring up your insomnia with your primary care physician, says Collop. Doctors often don't ask.
Before trying drugs or alternative medicine remedies, consult your doctor.