The sexual response cycle is how experts describe what’s going on inside your body that makes you feel and respond the way you do during sex.
Back in 1966, sex researchers William Masters, MD, and Virginia Johnson came up with the term. They defined four stages, or phases, of this cycle:
Phase 1: Excitement. As you get excited, your heart beats faster and your breathing gets heavier. Your skin may redden. More blood flows to your genitals. The clitoris swells and the penis gets erect. Nipples harden and the vagina may get wet. Muscles throughout your body tense up, boosting sexual tension.
Phase 2: Plateau. The changes in your body intensify. Breathing, heartbeat, and blood pressure rise. Muscle tension increases even more. The vagina swells and its walls turn a darker color. The clitoris becomes super-sensitive to touch. The testicles pull upward.
Phase 3: Orgasm. Sexual excitement reaches its peak. You feel a series of intense muscle contractions as your body releases the tension. The muscles of the vagina and the uterus contract. Muscles at the base of the penis tighten and release, releasing semen in an ejaculation.
Phase 4: Resolution. Now spent of your pent-up energy, your body returns to its pre-sex state. Your breathing calms. Muscles relax. The penis and vagina return to their original size and color. You may feel calm, satisfied, or tired out.
This four-phase cycle is a fairly simple way to describe the human sexual response. In reality, human bodies (and minds) are unique. The way we respond to sex doesn't always fit neatly into four ordered boxes.
"Since the Masters and Johnson model, we've learned much more," says Kristen Mark, PhD, the Joycelyn Elders endowed chair in sexual health education at the University of Minnesota Medical School. "One thing coming before another is pretty inaccurate to the human sexual experience."
Newer Views on the Sexual Response
For one thing, not every sex act leads to orgasm. Some people have sex without feeling any excitement. Others have multiple orgasms in a row, and they don't reach resolution.
The sexual response cycle model has gotten some updates over the years. In the late 1970s, sex therapist Helen Singer Kaplan, MD, PhD, added desire to the cycle. In her view, people need to be in the mood and emotionally ready for sex to get aroused and have an orgasm.
In 2001, Rosemary Basson, MD, a professor of sexual medicine at the University of British Columbia, threw the whole model for a loop -- literally. She created a circular sexual response model. Its main ideas are that people have sex for many different reasons, not just excitement. And each part of the cycle doesn't have to happen in any special order. For example, desire can come late in the process.
Orgasm isn't the only reward for having sex. You can do it for lots of other reasons, like to increase intimacy or make your partner happy. "Just because someone doesn't have an orgasm doesn't mean they aren't feeling some level of satisfaction," Mark says.
How Is Your Sexual Response Cycle Unique?
The sexual response cycle doesn't differ much by gender or sexual orientation, Mark says. But it can change from encounter to encounter. "It's super-individualized and really unique to each sexual experience."
For example, if you've desired someone for a long time and you finally have sex, the arousal phase might be faster. Early in a relationship, when the person you're dating is new to you, desire can come before arousal. Once you've been together for many years, you may get excited before you feel desire.
What Can Go Wrong?
Problems can happen at any phase of the sexual response cycle. Desire can dim, you may have trouble getting aroused, or you may not be able to reach orgasm.
Sometimes, a physical problem is to blame. For instance, erectile problems or vaginal dryness can make sex more difficult or painful. In turn, a physical problem can trigger an emotional response where you don't desire sex as much, Mark says.
But again, everyone is different. Even if you never get aroused, you might be just fine with your sex life.
Whether there’s a problem that needs help "comes down to your quality of life and how important this is to you," says Irwin Goldstein, MD, medical director of San Diego Sexual Medicine.
If you’re unhappy about your sex life, tell your doctor. You could have a treatable medical problem, like vaginal dryness or erectile dysfunction. Some types of medications can also hamper desire. Changing the dose or switching prescriptions might help.
If the problem isn't physical, your doctor can refer you to a sex therapist to help you work through any emotional, relationship, or psychological issues that are affecting your sex life. The therapist can teach you and your partner ways to manage problems like a lack of desire or trouble reaching orgasm.
It also helps to get to know your body's sexual response cycle. Pay attention to how you react. Do you feel arousal? What kinds of touch make you reach orgasm? By learning about your own response, "you can have a more satisfying experience and better communicate or tell your partner what you like," Mark says.
