Survey study, 1994
How does sleep change during the menstrual cycle?
Sleep brain wave patterns change noticeably across the cycle. A type of brain wave called spindle frequency was lowest 18 days before menstruation and highest 3 days before menstruation. This is very early evidence from only 5 women in one cycle.
What they did
5 healthy women aged 20-28 had 12-15 sleep recordings during one menstrual cycle, with daily measurements of body temperature and four hormones (LH, FSH, estrogen and progesterone).
What they found
Sleep spindle frequency (a type of brain wave during sleep) changed markedly across the cycle: it was lowest about 18 days before menstruation and highest 3 days before menstruation. Slow waves in sleep did not change. Stage 1 and REM sleep showed small changes. Other measures of sleep showed no clear changes.
What it means for you
Sleep patterns shift measurably during the menstrual cycle, mainly through changes in spindle frequency, which may reflect how hormones affect the brain. This could explain why some women experience sleep problems before their period. The study is very small (5 women followed for only one cycle), so much larger studies are needed to confirm these findings.
5
number of women
18 days
before period when spindle frequency was lowest
3 days
before period when spindle frequency was highest
About the study
- Original title
- Sleep spindle frequency changes during the menstrual cycle
- Authors
- Ishizuka Y, Pollak CP, Shirakawa S et al.
- Journal
- Journal of sleep research
- Year
- 1994
- Study design
- Survey study
- What was tested
- None
- Open access
- Yes
- Read the paper
- doi.org/10.1111/j.1365-2869.1994.tb00100.x