Chill your pillow for better premenstrual sleep

My Hormonology

Chill your pillow for better premenstrual sleep



Ever have trouble falling asleep or staying asleep during the second half of your cycle—which spans the day after ovulation through the day before your next period?

One reason is that estrogen falls twice during this phase—the first three days after ovulation, then again during the six days before your period. As this hormone drops, it can lower levels of brain chemicals that help manage sleep, such as serotonin and melatonin. And, it can make you more sensitive to common sleep disrupters, such as noise, light and aches. Unfortunately, there’s not a lot you can do about falling estrogen aside from trying to minimize its effects, for example, by putting in ear plugs or wearing a sleep mask.

Well, now researchers from Okayama University and Kansai University of Social Welfare in Japan have discovered another reason sleep may be harder to come by on these days in your cycle—and the fix may be as easy as popping your pillow in the freezer before climbing into bed.

Turns out, the slight one-half to one-degree rise in body temperature that naturally occurs on these cycle days due to elevated progesterone can be enough to keep you from getting sound sleep. Makes sense since a lower core body temperature is known to trigger the onset of sleep, so a higher core body temperature would interrupt this process, delaying sleep or making it less restful.

Fortunately, these researchers discovered that simply chilling your head as you sleep on these cycle days counteracts progesterone’s temperature-spiking effects, helping you nod off faster and get deeper, more restful zzzs.

In the study, participants laid their heads on a special sheet filled with chilled water to cool their scalps. But, you can simulate the effects by simply putting your pillow in the freezer for about 10 minutes before settling in to bed or turn on a gentle fan directed at your head to keep it cool.

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(1) Seiji Hamanishi, et al., “Head cooling during sleep improves sleep quality in the luteal phase in female university students: A randomized crossover-controlled pilot study,” PLOS ONE, published online March 25, 2019.

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