Most sexually active U.S. adults say typically have sex late at night but they prefer having sex during evening hours, a survey indicates. The Great American Sex Survey, commissioned by Adam & Eve, which sells adult products, indicates 52 percent of U.S. adults prefer to have sex during evening hours, 47 favor late-night sex, 33 percent prefer morning and 21 percent prefer afternoon sex. However, 48 percent of the survey respondents say they actually have sex mostly during late night hours; 45 percent say they have sex in the evening; 26 percent say they have sex in the morning and 13 percent say afternoon. Dr. Kat Van Kirk, Adam & Eve\'s resident sex expert, attributes this differentiation between \"preferring\" and \"doing\" to the realities of daily life. \"If we were to examine our natural biorhythms, hormonally our highest time for arousal is early morning for men and afternoon for women,\" Kirk, known as \"Dr. Kat,\" says in a statement. \"Unfortunately, sometimes people have sex because of their schedules ... not when their bodies are actually most receptive.\" The survey, conducted by an independent third-party survey company, involved 1,000 U.S. adults. No further survey details were provided.