Editor's Note: (Ian Kerner is a licensed couples therapist, writer and contributor on the topic of sex for CNN.)
(CNN) If you think you're too tired for sex, you're not alone.
According to a large new study, women over age 50 who get fewer than seven hours of sleep are less likely to report being sexually active than their peers who sleep more, a problem that increases with age.
Sleep disorders can also interfere with sex. Research suggests that men with obstructive sleep apnea, a condition marked by snoring and breathing difficulties, have decreased levels of sexual activity, possibly because they produce lower amounts of testosterone. Sleep apnea can also increase the risk of cardiovascular problems, which may be related to sexual dysfunction.
But the reverse appears to be true, too: Another recent study that looked at sleep and sex in college students found that for those in romantic relationships, every extra hour they slept corresponded to higher sexual desire, greater vaginal lubrication and a 14% increase in the chances of getting frisky the next day. That's probably because a good night's sleep leaves us feeling refreshed, relaxed and energetic -- all important for feeling sexy.
"This type of research builds on previous research demonstrating that lifestyle behaviors influence people's sexual lives," said Debby Herbenick, associate professor at Indiana University and president of the American Association of Sexuality Educators, Counselors, and Therapists.
Eating, exercise and stress levels can also influence sexual behavior, sexual desire and interest in sex. But sleep is one of the big categories, largely in our control.
"Dr. Alfred Kinsey noted this many years ago in his books, and more recent research supports it," Herbenick explained. "For example, a study published in the Journal of Sexual Medicine demonstrated that sleep apnea has been linked with sexual difficulties including erectile dysfunction and more global sexual difficulties. Other research has suggested that -- of the many reasons that menopause can impact sexual lives -- sleep deprivation (for example, due to night sweats) can be one of the reasons. And a 2015 study showed that women who slept longer at night were more likely to experience stronger sexual desire the following day ... It's clear that sex and sleep are closely tied together."
Although some couples may use fatigue as an excuse not to have sex rather than acknowledge deeper relationship difficulties, that's not always the case.
"Being too tired is the number one reason that women blame for their loss of desire," University of Florida psychology professor Laurie Mintz said. "A great number of women say that their primary issue is simply being too depleted to have interest in sex and not some looming relationship problem."
Of course, if you've scrimped on sleep and are feeling cranky and exhausted, an amorous romp is probably low on your to-do list.
Ironically, a sex drought can actually worsen sleep, setting you up for a vicious cycle of irritability. That's because sex helps us relax, unwind -- and, yes, fall asleep. Remember the classic stereotype of a guy dozing off immediately after sex? There's some truth to that, for both men and women.
The reasons are largely chemical in nature. After orgasm, our bodies release significant amounts of the "cuddle hormone" oxytocin, which lowers levels of the stress hormone cortisol, resulting in deep relaxation.
Sex also has gender-specific benefits. "For women, estrogen levels increase after sex, which can enhance a woman's REM cycle for a deeper sleep. In men, the hormone prolactin is secreted after orgasm and has been tied to sleepiness," explained licensed psychologist Rachel Needle, co-director of the Modern Sex Therapy Institutes.
Sex and sleep may be linked in other ways as well. To be able to fall asleep, we need to let go, said Lawrence Siegel, a clinical sexologist and certified sexuality educator at the Sage Institute for Family Development. Sex is similar, particularly for women, who typically need to be able to relax to have an orgasm.
"Many people experience a type of sleep disturbance where their defense system kicks in just as they're falling asleep and they're snapped back from the brink and now wide awake, heart racing due to the adrenaline and cortisol coursing through their veins," he explained. "Over many years of clinical experience, I have seen a connection between reports of this type of sleep disturbance and reports of the inability to orgasm."
So how can you break the no sleep/no sex cycle?
First, I recommend taking basic steps to promote good sleep hygiene: Make sure your mattress and pillow are comfortable, dim the lights at least an hour before bedtime, and use a white noise machine if your bedroom is loud. Try not to use your smartphone, tablet or other gadgets in bed; the light they emit can interfere with sleep. Make sure you're not using electronics as a way to avoid intimacy, a common diversionary tactic by people who may feel anxious about sex, according to certified sex therapist and licensed marriage and family therapist Amanda Pasciucco. And see your doctor if you think a sleep disorder might be interfering with slumber.
Finally, the best advice for fostering a healthy sex life is to just do it, even if you're tired. That may require some scheduling, but that can pay off in the long run.
"I recommend that couples have 'trysts' or planned sexual encounters," Mintz said. "These can be planned for times other than at night, when exhaustion is at its peak. Having trysts will also alleviate the all-too-familiar tension couples experience when crawling into bed at night, when one partner wants sex and the other feels too exhausted for a sexual encounter."
If you'd prefer to ease into things, that's fine, too. "You could say to your partner, 'I've had a long day and I'm exhausted; can we just snuggle tonight?' " certified sex therapist Francie L. Stone suggested. "That snuggling helps release oxytocin, which may result in sexual play and result in a good night's rest. Worst-case scenario, you're bonding and feeling closer." That's a win-win to me.