In a prospective cohort study designed to determine the associations of different measures of chronodisruption with time to conception (TTC), researchers from Washington University in St. Louis found that women who were trying to become pregnant who had more regular bedtimes took less time to conceive than those whose bedtimes were more erratic. They presented these findings at the ASRM’s Scientific Congress and Expo in Denver.

They recruited women from the community who were planning pregnancy and issued them actigraphs to wear continuously for two weeks to record and measure their activity and rest cycles. Participants were included in the study if they had at least 7 days of usable actigraphy data and a confirmed conception date. IVF patients were excluded.

The actigraphy data was used to ascertain the women’s times of sleep onset, waking, and sleep duration. Because most used alarm clocks, very little variation was observed in their wake-up times. Participants were placed in quartiles based on how much their sleep onset time varied from day to day. Women in the lowest quartile had variations of less than 67 minutes a day in the time they went to sleep each night. Bedtimes for women in the highest quartile varied by more than 138 minutes.

Of 176 participants, 75 were pregnant by the end of the year following the initiation of the study. Those who became pregnant were more likely to be white, have a lower BMI, and have higher levels of education and income. After adjusting for income and BMI, participants with less variation in the time they went to sleep had significantly shorter TTC than women whose sleep onset was less predictable. Neither sleep duration nor wake-up time was associated with shorter TTC.

Elizabeth Ginsburg, MD, member of ASRM’s board of directors, says in a release, “We know that adequate sleep is important to normal hormonal regulation and healthy functioning. This study indicates that, for women planning to conceive, the establishment of regular sleep habits could be advantageous.”