Immediate effect of blue-enhanced light on reproductive hormones in women

Neuro Endocrinol Lett. 2015;36(1):84-90.


Objective: Light is known to stimulate reproductive function in women. We here investigated the immediate effect of light on reproductive hormones, addressing the role of blue-sensitive (~480 nm) melanopsin-based photoreception mediating the non-visual effects of light.

Methods: Sixteen healthy women attended the Institute at ~07:25 (shortly after waking; sunglasses worn) twice in 2-3 days in April-May, within days 4-10 of their menstrual cycle. During one session, a broad-spectrum white-appearing light with a superimposed peak at 469 nm was presented against 5-10 lux background; during the other session, short-spectrum red light peaked at 651 nm with similar irradiance level (~7.0 W/m², corresponds to ~1200 lux) was used. Venous blood was taken at 0, 22 and 44 minutes of light exposure to measure concentrations of follicle-stimulating hormone (FSH), luteinising hormone (LH), prolactin, estradiol, progesterone and cortisol, and saliva was sampled to measure melatonin as a recognised indicator of the spectral-specific action of light.

Results: Melatonin values, as expected, were lower with white vs. red light (p=0.014), with the greatest difference at 22 minutes. Of the other hormones, only FSH concentrations differed significantly: they were mildly higher at white vs. red light (again, at 22 minutes; p=0.030; statistical analysis adjusted for menstrual cycle day and posture change [pre-sampling time seated]).

Conclusion: Moderately bright blue-enhanced white light, compared to matched-by-irradiance red light, transiently (within 22 minutes) and mildly stimulated morning secretion of follicle-stimulating hormone in women in mid-to-late follicular phase of their menstrual cycle suggesting a direct functional link between the light and reproductive system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Estradiol / blood
  • Female
  • Follicle Stimulating Hormone / blood*
  • Humans
  • Hydrocortisone / blood
  • Light*
  • Luteinizing Hormone / blood
  • Melatonin / metabolism*
  • Menstrual Cycle / blood*
  • Progesterone / blood
  • Prolactin / blood
  • Young Adult


  • Progesterone
  • Estradiol
  • Prolactin
  • Luteinizing Hormone
  • Follicle Stimulating Hormone
  • Melatonin
  • Hydrocortisone