The pairs were then videotaped, discussing subjects that they usually rowed about. 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. In males, the bonding hormone helps make the prostate and seminal glands to contract. Research by scientists at the University of California, San Diego, found men who exercised had a boosted libido. And why, late at night, when a woman is in the mood for love, is her man just lying there, snoring? Sex hormones take longer to increase. It all comes down to hormones. 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. 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. However, an after-work gym session can boost the libido of both genders. But the more attractive a woman feels, the more likely it is that she will want to jump into bed with him. Not good news for England fans, then! 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? It is also kept in balance by oestrogen and progesterone. Researchers believe the reason is that music may make women feel more relaxed, bonded and in turn more sexual, while in men it calms their aggression and in turn reduces their levels of testosterone.