It's a common situation: What once was hot and heavy has gone, well, rather tepid. Most couples chalk this up to the natural progression of a long-term relationship. But it could be that your health habits outside the bedroom are to blame for your struggles inside it. 

"People think sexual health is all about sexually transmitted infections and birth control," says Eric Garrison, a clinical sexologist and author of Mastering Multiple-Position Sex. "But our sex lives are linked intrinsically to our general health." 

Here, the unhealthy behaviors that might be keeping you and your partner from the best sex of your lives.

You're not sleeping enough

Not only does a lack of Z's leave you fatigued and prone to illness, but it has also been shown to have sexual repercussions—for both men and women, according to a study in Brain Research. How much shuteye do you need? The sweet spot is five to seven complete REM cycles, or seven to nine hours per night, says Garrison.

You're neglecting your physical fitness

Aerobic capacity and stamina, as well as strength and flexibility, are just as valuable between the sheets as they are on the streets in your day-to-day life. Research also points to the benefits of exercise right before you plan to get busy. Getting your heart rate up improves blood flow, which stimulates your sex organs, says Nicole Prause, Ph.D. which uses brain stimulation to treat problems related to sexual desire. Any increase in exercise is worthwhile. "If you add just a 30-minute walk a day or begin a yoga practice, you'll have better sex than before you started," says Garrison.

You have bad bedroom juju

You've probably heard you should make your bedroom a haven for sleep. The same goes for sex. If the room isn't conducive to intimate relations, you're fighting an uphill battle, says Garrison. You should avoid doing work or using your laptop in bed, clear the kids' toys off the floor, and remove anything that keeps you from focusing on the task at hand, he suggests. "One client of mine has a photo of his in-laws on the dresser next to his bed," says Garrison. "You want your sexual environment to be stimulating, not distracting!"

You're missing out on essential nutrients

Eating a balanced diet ensures you get all the vitamins and minerals that have been linked to proper sexual functioning. "Zinc is vital for male sexual health," says Garrison. "We talk of oysters being aphrodisiacs, and they're an excellent source of zinc." He also points to the importance of B vitamins like niacin—found in salmon, chicken, and tuna—when it comes to energy production and blood flow, which are both important for sexually active men and women

You're eating foods that fuel flatulence

There's no research-backed link between a fondness for beans and broccoli and decreased sexual enjoyment. But the potential for embarrassment can make you feel anything but sexy, says Prause. If you're planning a romantic evening, best to steer clear of stuff you know will make you gassy.

You're drinking excessively

Too much alcohol can lead to "inorgasmia," or the inability to orgasm. And chronic alcoholism, even after years of sobriety, appears to cause a long-term detriment to sexual performance, research shows. But up to three glasses of wine can actually boost libido in women. "At blood alcohol levels up to 0.1, women respond more easily and report being more turned on," says Prause. A BAC of 0.03 roughly translates to a glass of wine an hour, and a BAC of 0.1 is about three glasses in that amount of time.

You're a smoker

Need yet another reason to quit? Smoking messes with blood flow, which is bad for your heart and your sex organs, shows research from the Mayo Clinic. "Smoking is strongly related to erectile dysfunction," says Prause. "There are even antismoking campaigns that talk about this." So listen up and don't do it… if you want to, you know, do it.

You're on certain medication

If you just never feel like having sex, the medication you're taking could be the culprit. "The FDA doesn't require testing or reporting of sexual side effects," says Prause. "And 70 percent of the time, it's a medication that's causing inorgasmia." She says poor libido is also a common issue. Antidepressant drugs are notorious for lowering sexual desire, and research backs up those rumors. Also, anything that dries out your mucus membranes—like antihistamines—can contribute to vaginal dryness. Talk to your doc about other options if you suspect your meds are what's behind your lack of libido. 

You're not self-pleasuring

A lot of people associate masturbation with randy teenagers, but the act of self-pleasuring has long been suggested as a treatment for sexual disorders. "Masturbation helps you become more comfortable with what you like and helps you express what you like to a partner," says Garrison. Research from the Archives of Sexual Behavior suggests masturbation may even fuel sexual desire.