"Not tonight, I have a headache."

We've probably all used that one at some point. It feels easier to offer up a headache or other malady than it does to say no. There are times when we just don't want to have sex. Sometimes there is a specific reason; often it's just a vague lack of interest.

But there are good reasons to have sex, even if we don't think we want to. Low female sexual desire is a topic I've written on and recently given talks about. And, although everyone can probably recall a time when they didn't want sex, low sexual desire is a little different. While there are a lot of reasons behind it, the key thing to remember about it is that the less sex you have, the less you tend to want.

So, while there are definitely good reasons to avoid sex, the problem is that low desire can stem directly from that avoidance as well.

Here we'll look at five good reasons to have sex even if you don't think you're in the mood.

Sex Increases Arousal and Can Improve Your Mood!

As I've mentioned before, there are medical reasons why sexual activity is good for us. Arousal and sexual activity increase blood flow to vaginal tissues and can help eliminate or reduce the chances of vaginal atrophy. Sex strengthens pelvic floor muscles, encourages the production of natural lubrication, and more. Having sex also stimulates the production of oxytocin, the "feel good" hormone. In other words, when we have highly pleasurable or orgasmic sexual experiences we experience a sort of sexual high. We just feel better!

Sex Increases Desire

The catch-22 of avoiding sex when you don't feel like it is that this can reduce your desire for sex overall. Want to feel more sexual desire? Have more sex. But, perhaps more important here is to communicate better with your partner about how you're really feeling. Research has shown that women who report being in good relationships were better able to negotiate their sexual agency because they felt safe and respected as people by their partners, not just as sexual objects. Those who could talk to partners about sex also discussed being more interested in sex and more satisfied with their sexual experiences overall.

When we can practice asking for what we want and talking positively about sex, we feel better about ourselves and our partners. This all leads feeling more sexual desire - that's one of the conclusions in the study Negotiating Sexual Agency: Postmenopausal Women's Meaning and Experience of Sexual Desire, conducted by Dr. Jill Wood and colleagues. What this study is really saying is that having sex and having a good relationship make us want more of both.

Sex Is Good for Your Relationship

In another study, researchers looked at individuals who didn't necessarily want to have sex and their motivation for doing it anyway. One group had sex to avoid negative outcomes (an angry partner, for example) and the others had sex for positive, or "approach motivated" reasons. They found that people who talked about their "approach-motivated sexual experiences reported feeling more desire for their partner, more satisfied with their sex life, and happier with their overall relationship compared to people who reflected on avoidance-motivated sexual experiences or people in the control group."

The act of having sex, even when it wasn't desired, led to stronger relationships, but only if individuals were doing so in order to maintain a good relationship. The individuals involved (the study involved 396 people) seemed to understand the connection between intimacy and overall relationship satisfaction. They had sex in order to strengthen or maintain their relationship.

Physical Contact Increases Connection and Desire

There is a myth that desire arises spontaneously for all individuals. One kiss and we're ready to throw off the clothes. Spontaneous desire is more likely to happen for men than women, while most women experience something Emily Nagoski refers to as responsive desire. In other words, desire arises in response to actions, touch, or other stimuli. What this means is that women who don't feel like having sex may find themselves more enthusiastic if they are willing to engage in some of the preliminaries in order to create feelings of desire.

In my book, "Inviting Desire," I offer suggestions for things women can say to open themselves to more sexual possibilities, such as "I'm not sure I'm in the mood, but I'm willing to try some cuddling, kissing, touching, and see how I feel." This kind of statement allows for the possibility of intimacy while clarifying that the speaker has that option to change her mind. It indicates a willingness to connect and the awareness that desire could arise as a result.

Sex Makes Our Partners Happy

Sometimes we have sex even if we're not in the mood for the simple act of pleasing a partner. And that's a great reason, as long as it's not driven by a sense of obligation. The intimate bonds created between two people are based on respect, love or affection, and a desire to both give pleasure and find pleasure in taking care of a partner's needs. Because you care, you want to make them feel good. It's the gift without expectation, the paying it forward, the act of love.

There will always be times when we don't think having sex is worth the time, the effort, the reward, or whatever (insert your usual reason). In those moments, we may forget the many benefits associated with a satisfying sexual relationship. See if you can figure out what gets in the way of your desire for sex. What might make it better? What do you need or want to do? How can you create the environment, emotionally or physically, to allow for the blossoming of sexual desire?