Survey study, 2025
Does being underweight affect sleep differently across the cycle?
Underweight and normal weight women had similar sleep overall. Underweight women woke more during the first part of their cycle and had lower sleep hormones during the second part.
What they did
Researchers followed 28 female university students aged 18-24 in Japan (10 underweight and 18 normal weight) across their menstrual cycles. They measured sleep using daily questionnaires, sleep sensors under the mattress, and a sleep hormone measured in urine.
What they found
Underweight and control groups showed no significant differences in sleep patterns across cycle phases on questionnaires or sensors. Underweight women experienced more difficulty staying asleep during the follicular phase. A higher percentage of underweight women (7 of 10) had decreased sleep hormone levels during the luteal phase compared to the control group (3 of 13).
What it means for you
Being underweight may affect sleep quality, particularly the ability to stay asleep and possibly hormone levels. This is a very small preliminary study from Japan. The main limit is only 28 women were studied, so results may change with larger numbers.
28
women studied
10
were underweight
7 of 10
underweight had low hormone levels in luteal phase
About the study
- Original title
- Sleep characteristics in underweight young females across their menstrual cycles: A sleep-monitoring survey study with preliminary results
- Authors
- Kayaba M, Yajima K, Nogami M et al.
- Journal
- Journal of sleep research
- Year
- 2025
- Study design
- Survey study
- Participants
- 18
- What was tested
- None
- Read the paper
- doi.org/10.1111/jsr.14254
Topics
Related studies
Randomised trial, 2026
Does a warm footbath help PMS symptoms and sleep quality?
Survey study, 2026
What dietary, lifestyle, and psychological factors are associated with PMS in young women?
Survey study, 2026
Does exercise help college women with period problems and mental health?
Survey study, 2026
Do nursing students with PMS experience excessive daytime sleepiness?
Survey study, 2026
What factors most strongly drive PMS severity in female engineering students?
Survey study, 2025
Does sleep quality affect the severity of premenstrual symptoms?