58. Gender differences in sleep11 September 2010 at 17:17 | Posted in Circadian rhythm | 2 Comments
Tags: Circadian rhythm, Core body temperature, DLMO, Entrainment, Melatonin, MEQ
I’ve earlier seen hints that there are differences in men’s and women’s sleep timing. Now a new study confirms that and has also found differences in the quantity of melatonin secretion and in the daily temperature amplitude.
The study participants were normal sleepers: 28 women and 28 men, ages 18-30, matched in pairs for age, habitual bedtime, habitual wake time and MEQ-results. Under strictly controlled conditions, so-called constant routine, their core body temperatures and melatonin levels were measured.
The women reached higher levels of melatonin in the blood.
The men had a greater amplitude in body temperature throughout the day and night.
The illustration shows the significant differences in sleep timing between women and men, on average. In each of the 28 matched pairs of participants, significant differences were found between the women and the men with regard to the intervals
- between DLMOn and bedtime,
- between wake time and DLMOff, and
- between temperature minimum and wake time.
The women were sleeping and waking at the same clock time, but at a later biological time than the men.
- MEQ = the Morningness-Eveningness Questionnaire by Östberg and Horne
- DLMOn = Dim Light Melatonin Onset
- DLMOff = Dim Light Melatonin Offset (Here, based on blood level, not offset of synthesis.)
Reference: Cain, Sean W., Christopher F. Dennison, Jamie M. Zeitzer, Aaron M. Guzik, Sat Bir S. Khalsa, Nayantara Santhi, Martin W. Schoen, Charles A. Czeisler and Jeanne F. Duffy. Sex Differences in Phase Angle of Entrainment and Melatonin Amplitude in Humans. Journal of Biological Rhythms 2010 25: 288. DOI: 10.1177/0748730410374943
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