--- title: How does light therapy affect hormone levels in women with PMDD? description: Light therapy shifted hormone timing in women with PMDD in different ways depending on the time of day. Women with PMDD had naturally higher prolactin levels url: https://niyora.com/research/papers/neuroendocrine-effects-of-light-therapy-in-late-luteal-phase-dysphoric-disorder-1994/ --- - [Niyora](https://niyora.com/) - [Research](https://niyora.com/research/) - [Library](https://niyora.com/research/library/) - How does light therapy affect hormone levels in women with PMDD? Randomised trial, 1994 # How does light therapy affect hormone levels in women with PMDD? Light therapy shifted hormone timing in women with PMDD in different ways depending on the time of day. Women with PMDD had naturally higher prolactin levels throughout their cycle compared to women without PMDD. Moderate study design 20 women with PMDD and 11 normal controls ## What they did RCT with 20 women with PMDD and 11 normal controls. Hormone levels (cortisol, prolactin, TSH, temperature) were measured during two menstrual cycle phases. Women received three light treatments in random order: bright white morning light (2500 lux, 6:30-8:30 AM), bright white evening light (2500 lux, 7-9 PM), or dim red evening light (less than 10 lux) for 1 week each. ## What they found In normal controls but not in women with PMDD, cortisol peak was delayed during the late luteal phase compared to the midfollicular phase. In PMDD, prolactin peaks and amplitude were higher, peaked earlier, and body temperature amplitude was higher during both cycle phases. After light treatment, prolactin remained higher in PMDD. Bright light shifted cortisol timing in both groups. Morning light increased prolactin nadir in both groups. Bright evening light increased TSH nadir in PMDD but decreased it in controls. ## What it means for you Women with PMDD have different hormone patterns than women without it throughout their cycle. Light exposure affects these hormones differently in PMDD versus normal women. The study measures hormones but does not clearly show whether these hormone changes improve symptoms. Very small sample sizes limit confidence in the findings. 20 women with PMDD 2500 lux brightness of white light 1 week duration of each light therapy ## About the study Original title Neuroendocrine effects of light therapy in late luteal phase dysphoric disorder Authors Parry BL, Hauger R, Lin E et al. Journal Biological psychiatry Year 1994 Study design Randomised trial What was tested Bright white light (morning or evening at 2500 lux) or dim red evening light (less than 10 lux) for 1 week Read the paper [doi.org/10.1016/0006-3223(94)91210-6](https://doi.org/10.1016/0006-3223(94)91210-6) ## Topics [Premenstrual syndrome (PMS)](https://niyora.com/research/topics/condition-pms/)[Premenstrual dysphoric disorder (PMDD)](https://niyora.com/research/topics/condition-pmdd/)[Menstrual cycle and mood](https://niyora.com/research/topics/condition-cycle-mood/)[Low mood and depression](https://niyora.com/research/topics/symptom-depression-mood/)[Sleep and insomnia](https://niyora.com/research/topics/symptom-sleep/)[Stress](https://niyora.com/research/topics/symptom-stress/)[Light therapy and sleep deprivation](https://niyora.com/research/topics/treatment-light-therapy/) Research tells you what helps on average. Niyora helps on the day it hits. Calm down, see it another way, and decide what to say, with a PMS and PMDD app built by a doctor. ## Related studies Survey study, 2021 What factors are related to premenstrual syndrome in high school students? Study, 2011 Does bright morning light reset the body clock differently in women with PMDD? Study, 2010 Are women with PMDD more sensitive to how light affects sleep hormones? Review, 2024 What do brain wave patterns show about PMS and PMDD? Survey study, 2026 What hormonal and psychological factors affect PMS symptoms? Survey study, 2025 Are premenstrual dysphoric disorder symptoms, stress, and sleep quality linked in female nursing students? Ask AI about this page Copy prompt ChatGPT ↗ Claude ↗ Perplexity ↗ Google AI Mode ↗ Grok ↗