The pairs were then videotaped, discussing subjects that they usually rowed about. According to a study by the University of Texas, women who had 20 minutes of cardio exercise were more aroused by seeing an erotic film than women who had not exercised. In women, it helps to spark uterine contractions that move the sperm towards the ovaries. In one study of women athletes, their testosterone levels significantly increased after long runs. Sex hormones take longer to increase. It all comes down to hormones. However, when confronted with a sexy person, a man who naturally already has higher testosterone levels is likely to be more flirtatious with them. Studies found the longer and deeper a man has slept, the higher his testosterone levels. The tests were given two weeks before they saw their partners, the day before, before sex, the day after sex and three days after the pair were separated. Levels of sex hormones also spike in women after exercise. When the levels are lower, her climaxes are less intense and centred mainly around the sexual organs. And why, late at night, when a woman is in the mood for love, is her man just lying there, snoring? The hormone is also needed to trigger muscle growth and sperm production. As both sexes get ready for the day, levels of the stress hormone cortisol rise to help them wake up — and help dampen the effect of sex hormones. A good kip is another reason a man may feel even more amorous in the morning. Could not subscribe, try again laterInvalid Email Why is it that a man feels at his sexiest when he wakes up in the morning but a woman wants to go back to sleep? But the more attractive a woman feels, the more likely it is that she will want to jump into bed with him.