If you are better about scheduling in your spin classes than your nookie sessions, you might want to rethink your calendar this month. While most of us see sex as "fun time" (and it should be that, too!) and something we get to do when all our other obligations are satisfied, the evidence is mounting of several benefits of sex.


You might be justified in moving it from "when I can get to it" to "legit priority": here's how even a quickie can benefit our bodies and minds, as well as our relationships:


1. It's a free mood booster: Happiness is priceless, right? When both men and women orgasm, oxytocin (a.k.a. the "love hormone") is released, which tends to lead to feelings often described as happiness. This free brain chemical calms anxiety and fear and increases trust and contentment. Positive interaction with friends and family increases the chemical somewhat, self-arousal even more so and sex with a partner you care about tops the list. 


2. It increases immunity: Having sex at least once or twice a week can boost immunity, according to a study by Wilkes University in Pennsylvania. "I'd rather have frequent sex than take cold medicine any day of the week," says Stefanie Iris Weiss, author of "Eco-Sex: Go Green Between the Sheets and Make Your Love Life Sustainable."


3. It burns calories: You'll see all kinds of estimates about how many calories sex takes, but the truth is that like any physical exertion, it depends on how vigorous it is and how long it lasts. Weiss says that when talking positions, the woman on top burns the most calories (for a woman, and vice-versa for men) and that standing up copulation burns more energy than in-bed lovemaking. The key to burning more calories is going longer — 30 minutes will require more energy than 20 minutes.


4. It reduces pain: "Sex can reduce pain and PMS symptoms," says Weiss. "I often tell friends suffering from cramps to go for a sex session rather than an Advil. Regular sex also strengthens pelvic floor muscles — and it's a lot more interesting than a Pilates class."


5. It improves men's health: Guys who have regular sex have healthier hearts, or in science-speak, "Our research found that a low frequency of sexual activity predicted new cardiovascular events," Susan Hall, Ph.D., told Men's Health. It may also protect against prostate cancer, according to research done at the National Cancer Center.


6. It can help you sleep better: "Sex reduces stress, so it's a great curative for those of us who are overworked and don't get enough sleep," says Weiss, who credits the oxytocin for this effect.


7. It can help you get in touch with your body: "Sex can teach us how to have a better relationship with our own bodies," says Weiss. Especially for women, who tend to suffer from poor body-image more than men, being comfortable and communicative during sex can be liberating and affirming. Women can learn from a caring sexual relationship that one's body can be about a physical relationship that's based on more than how it looks — and focuses more on how it feels.


8. It gets you — and keeps you — closer to your beloved: Whether it's the chemicals like oxytocin, the time spent skin-to-skin with your favorite person, or the post-sex pillow talk, sex can help us get closer to each other, and gives us a very personal "check in" time, especially for those partners with busy lives that pull in opposite directions.


Also on MNN: What's not green about sex?



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Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.

8 surprising benefits of sex
Rethink your calendar this month. While most of us see sex as 'fun time' and something we get to do when all our other obligations are satisfied, the evidence i