---
title: How does sleep change during the menstrual cycle? | Niyora
description: 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
url: https://niyora.com/research/papers/sleep-spindle-frequency-changes-during-the-menstrual-cycle-1994/
---

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- How does sleep change during the menstrual cycle?

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.

 Early or limited evidence

5 healthy women aged 20-28

## 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](https://doi.org/10.1111/j.1365-2869.1994.tb00100.x)

## Topics

[Sleep and insomnia](https://niyora.com/research/topics/symptom-sleep/)

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