The moment your clothes come off, and you’re in bed with your partner turning up the heat in between the sheets, your heart is racing, blood is pumping, and muscles are tensing up. As you and your partner strive to reach the big “O” — an orgasm — your body is filled with the intensity and tingling sensations of a promising sexual climax. Overcome with a feeling of euphoria as a surge of blood rushes to the genitals, what exactly happens to the brain when you have an orgasm?

Genitals Communicate with the Brain

During sex, our brain acts as a “pleasure center” to let us know what is enjoyable and what is not. The different nerves in the genitalia communicate with the brain about the sensation experienced. This can help explain why sensations can be perceived differently depending on what part of the body the person is being touched. A French study found women experience two different kinds of orgasms — clitoral and vaginal — that differ in blood flow and sensations. These orgasms also contain a different set of nerves. The clitoris, which extends along both sides of the vulva underlying the labia minora, is erectile with arousal as it has more than 8,000 nerve endings.

For men and women, there are four types of nerves responsible for sending information to the brain during an orgasm. The hypogastric nerve transmits signals from the uterus and the cervix in women, and from the prostate in men; the pelvic nerve transmits signals from the vagina and cervix in women, and from the rectum in both sexes; the pudendal nerve transmits from the clitoris in women, and from the scrotum and penis in men; and the vagus nerve transmits from the cervix, uterus, and vagina in women.

Neurochemicals Give Off the 'Euphoric' Feeling

The “cloud nine” feeling reported by many during sex is linked to the nerves sent to the brain’s pleasure center, or reward circuit. The sexual arousals felt in the body flood the brain with a surge of neurochemicals, which are chemical messengers that forge emotions, feelings of attachment, and even love, according to Psychology Today. The level of pleasure is contingent on the release of these chemicals that can be used to measure the intensity of your climax. The areas of the brain impacted by sexual arousal include the amygdala, nucleus accumbens, ventral tegmental area (VTA), cerebellum, and the pituitary gland.

Male and Female Brain Similar to Being on Heroin

Although both sexes tend to engage in different behaviors during sex, the brains of men and women are not all that different. During an orgasm, the lateral orbitofrontal cortex — the brain region behind the left eye — shuts down during an orgasm. This region is considered to be the voice of reason and controls behavior. The brain of both a man and woman is said to look much like the brain of a person taking heroin during an orgasm, according to a study published in the Journal of Neuroscience.

A difference between the two sexes lies in the periaqueductal gray (PAG) — the part of the brain that is activated when a woman has sex. The PAG is not activated in men when they reach an orgasm. Moreover, women will experience a decrease in the amygdala and hippocampus — which help monitor fear and anxiety — during an orgasm.

Women Can’t 'Fake It Till They Make It' (in an MRI)

Women are notoriously known for faking orgasms out of pity for their partners, or to convince themselves the sex is good, but an MRI scan can show the truth. In an MRI scan, the brain is able to identify whether women were actually experiencing an orgasm. When the women were asked to fake an orgasm, their brain activity increased in the cerebellum and other areas related to movement control, but this brain activity was not seen during an actual orgasm.

Overall, an orgasm is the body’s physiological response to sexual stimulation, and involves involuntary body movements and vocalizations. This has a similar effect on the brain to that of an addictive substance, such as heroin. Men and women tend to have similar brain activity during an orgasm, despite the different emotions and behaviors displayed by both genders.