Want more sex? Get better sleep. Want better sleep? Have more sex

Editor’s Note: Ian Kerner is a licensed couples therapist, writer and contributor on the topic of sex for CNN.

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Being too tired is the No. 1 reason women blame for loss of desire

After orgasm, our bodies release the "cuddle hormone" oxytocin, causing deep relaxation

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 relati