Diurnal and weekly, but no lunar rhythms in humans copulation.
Palmer JD, Udry JR, Morris NM.
PIP: A study was conducted to determine the solar day, lunar day, and weekly rhythms in human copulatory behavior. The study subjects were young married couples, with a median age of 25, living in North Carolina. All avoided conception by means other than oral contraception (OC). The husband and wife were paid $1.00/day for completing a questionnaire each morning, reporting whether they had engaged in intercourse in the previous 24 hours. Subjects recorded copulatory events to the nearest hour. Discrepancies between report pairs on whether intercourse had occurred were less than 1%. The data presented are from 2 studies, 1 consisting of 48 couples, reporting 1230 copulations between September 3 and December 2, 1973, and the other of 30 couples, over 711 copulations recorded between June 8 and September 5, 1974. Only the women's responses are reported here; menses were ignored. The average copulation rate/couple was 2.48 times/week in the 1973 study and 2.34 times/week for the 1974 group. The extreme values were 7.4 times/week and 0.64 times/week. Combining all the data produced a mean rate of 2.44 copulations/week. Mean daily copulatory rates for both studies were so similar that the data were pooled into a single curve for presentation. The copulation rates on weekdays were very similar, with just under 1/3 of the sample copulating each day. The average daily rates increased to 40.3% on Saturdays and to 52.6% on Sundays. The rate on Friday differed significantly from Saturday and Saturday from Sunday. 38.3% of the week's copulations occurred on the weekend. On 10.6% of the days that couples copulated, they did so twice or (rarely) 3 times, in a single day. Single-couple multiple copulations were 3.4 times more common on Sundays than on a weekday and 1.6 times more common than on Saturdays. 61% in 1973 and 66% in 1974 of all weekday copulations took place between the hours of 10:00 p.m. and 1:00 a.m. For the weekend it was mainly the augmented copulation rates during the mornings and afternoons that caused the weekend copulatory rate to be significantly higher. In the 1974 study, the women recorded whether they had experienced orgasm during intercourse. As a group, they failed to reach orgasm in 29.4% of their encounters. Between the hours of midnight and 11:00 a.m., 38.6% of all copulation failed to result in orgasm for the women, but between noon and midnight, the rate improved significantly.
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PMID: 7200945 [PubMed - indexed for MEDLINE]