What turns you on? The answer varies greatly from person to person. But what actually happens beneath the surface when we start feeling in the mood?
The first scientists to seriously study the physiology of sex—or at least to break the taboos around discussing it—were William Masters and Virginia Johnson. These sexologists began their research in the 1950s (and later married in 1971). Dr. Angela Wright, a GP and clinical sexologist based in Yorkshire, explains: “They developed what’s known as the four-stage model, which describes how the body becomes aroused, reaches a plateau, experiences orgasm, and then returns to baseline.”
“But what’s interesting,” she adds, “is that this model doesn’t address actually wanting sex. It was as if desire just appeared out of nowhere, rather than being part of the process. Later models have explored what makes humans want to have sex. Typically, we see that in male bodies, desire often feels more like hunger. In female bodies, especially in long-term relationships, about 75% of the time it’s more like walking into a supermarket, smelling bread, and then realizing you’re hungry.”
In other words, part of our desire seems spontaneous, while another part responds to environmental cues—some of which we associate with past “rewards.” Hormones like testosterone and estrogen do influence how often we think about sex, but much of the response is behavioral.
Dr. Ben Davis, a GP specializing in sexual medicine and therapy for men, says: “Signals from sight, touch, memory, fantasy, or emotional connection activate networks in the brain’s limbic system and hypothalamus. These signals then travel through the nervous system to the body. But people experience arousal differently. Some notice physical sensations first—warmth, genital tingling, a quickened pulse. Others need mental or emotional stimulation before their body responds. Most of us fall somewhere in between. Understanding whether you’re more body-first or mind-first can help you create better sexual experiences.”
Alix Fox, a journalist and PhD researcher in sexual wellbeing at University College London, adds: “Sexual arousal is a much more complex and multifaceted process than the straightforward, primal response it’s often assumed to be. Recognizing this can help us be kinder to ourselves if our libido isn’t working as we’d like, or if we experience kinks that confuse us.”
After these initial signals, the parasympathetic nervous system (often called the “rest and digest” system) takes over, triggering the release of nitric oxide. “This relaxes smooth muscle and increases blood flow to erectile tissue in the penis, clitoris, and vulva, leading to engorgement, lubrication, and heightened sensitivity,” explains Davis. “At the same time, neurochemicals like dopamine drive desire and motivation, while oxytocin supports emotional connection and touch. Together, they help shift the body from a state of vigilance into one where sexual response is possible.”
While some of the mechanics are similar, what happens next depends on the body involved. “In women’s bodies, there’s an arousal response sometimes called ‘tenting,’ where the uterus lifts and the upper vagina opens to facilitate penetration,” says Wright.
It’s also helpful to note that there are two different ways that…People can experience the rush of blood that leads to penile or clitoral erections. First, there are reflex erections, which originate from the spinal cord without any conscious thought about sex—they essentially flush the area with a surge of blood to deliver oxygen and maintain tissue health. This is crucial because the body normally suppresses sexual arousal, keeping erectile tissues somewhat blood-deprived. Without these reflex erections due to age or illness, the tissues can gradually deteriorate and become less responsive.
The other type of arousal comes from thinking about or desiring sex, or from sexual touch. “That signals that sex might happen and prompts the body to prepare,” says Wright.
In the penis, when blood flows in, it fills rods of erectile tissue. Eventually, these compress the surrounding veins that normally drain blood, trapping it and making the tissue rigid enough for penetration. “In female bodies, things work a bit differently,” Wright explains. “Blood must continue flowing in to sustain a clitoral erection, which is why sensations can sometimes feel like they ebb and flow.”
Besides nitric oxide, key neurotransmitters involved in this process include dopamine, oxytocin, noradrenaline, adrenaline, and acetylcholine. Their balance shifts depending on which stage of the sexual response cycle we’re in. Dopamine drives motivation, desire, and reward; adrenaline contributes to excitement; and oxytocin supports bonding and trust, especially after orgasm. Importantly, for all of this to occur, the sympathetic nervous system (“fight or flight” mode) must remain calm. Stress or anxiety can act as a biological brake, constricting blood vessels and halting the process.
“Good sexual experiences require a balance of sympathetic arousal and parasympathetic safety—you want to feel excited, not anxious,” says Davis. “If sympathetic drive is too high due to fear or hypervigilance, it can shut down arousal.”
What does this mean for you? First, if you’re stressed about other things, don’t feel bad for lacking interest in sex. “An overloaded brain, overthinking, stress, or anxiety can all hinder our ability to experience sexual arousal and to focus on pleasurable sensations that encourage it,” says Kate Moyle, a psychosexual therapist and author of The Science of Sex. “Stress and anxiety commonly disrupt both pleasure and sexual functioning.”
It’s also important to recognize that a drop in desire may signal other changes in your body or life. “Women after menopause or while breastfeeding may have reduced sensation, which means they get less reward from engaging in sex. As a partner, it’s important to understand this and help create opportunities for arousal,” says Wright. “Being honest about what brings you pleasure is key, because humans are simple: we repeat what we enjoy. If something makes you feel bad, ashamed, or leads to negative consequences, your behavior will naturally change.”
For some, sexual symptoms can be early signs of cardiovascular, hormonal, or mental health issues. “Many assume weaker erections or fading desire are just part of aging, but persistent changes are worth discussing with a doctor,” says Davis. “Gradually worsening erectile difficulties, in particular, are well-established indicators of underlying health problems.”Erectile dysfunction can be an early predictor of future cardiovascular disease, as the small arteries in the penis are affected by vascular issues sooner than the coronary arteries.
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“If you asked most people to define desire, they would often include the word ‘spontaneous.’ That version is overrepresented in our culture and media,” says Moyle. “In reality, for many people—especially those in long-term relationships—desire tends to be more responsive. This means we need to actively seek it out and create opportunities. If we wait for ‘the mood to strike,’ it could be a long wait, since desire has to compete with many life factors and other priorities.”
“It becomes about a willingness to get turned on,” says Wright. “That’s about creating desire. To use a food analogy: how often have you been full, not wanting to eat anything else, until someone puts a cheesecake in front of you and suddenly you want a slice? It’s about creating scenarios where you or your partner will ‘see the cheesecake.’” Or whatever else they might find appealing.
Frequently Asked Questions
FAQs About Sexual Arousal and Physical Responses
Beginner Questions
What is sexual arousal
Sexual arousal is the physical and mental state of being sexually excited or turned on Its a natural response triggered by thoughts sights touch or other stimuli
What physically happens to a mans body when hes aroused
For men arousal typically involves increased blood flow to the penis This causes the spongy tissues inside to fill with blood resulting in an erection
What physically happens to a womans body when shes aroused
For women arousal involves increased blood flow to the genital area This can cause swelling lubrication and a feeling of warmth
Is arousal the same as desire
Not exactly Desire is the interest in sexual activity while arousal is the physical and mental response that follows You can have one without the other
Do both men and women get aroused the same way
The mental and emotional pathways to arousal can be very similar but the visible physical signs differ Mens arousal is often more externally obvious than womens internal responses
Common Processes Variations
Why does lubrication happen for women during arousal
Increased blood flow causes fluid to seep through the vaginal walls creating natural lubrication This reduces friction and makes sexual activity more comfortable and pleasurable
Can you be mentally aroused but not show physical signs
Yes This is sometimes called a mindbody disconnect Stress medication fatigue or hormonal changes can prevent the body from showing the expected physical signs even if you feel mentally turned on
Can you have physical signs of arousal without feeling mentally turned on
Yes The body can react to direct physical touch or friction with lubrication or even an erection without conscious sexual desire This is a reflexive response
Whats the point of these physical changes
They prepare the body for potential sexual activity Erections facilitate penetration and lubrication makes penetration more comfortable They also enhance physical pleasure for both partners
Common Questions Concerns
Is it normal for arousal to happen at inconvenient times
Yes especially during puberty or due to hormonal fluctuations Spontaneous arousal is a normal sign of a healthy nervous and
