Randomised trial, 1987
Does a brain opioid system cause the drop in hormone pulses seen during sleep early in the cycle?
Yes, it looks that way. Blocking opioid receptors with naloxone stopped the usual sleep-related slowdown of LH hormone pulses, and even increased pulse frequency during sleep, pointing to opioids as the cause.
What they did
10 women with normal cycles were studied on days 3 and 4 of their cycle. Each received a 24-hour infusion of naloxone (a drug that blocks opioid receptors) and, on a separate occasion, a salt-water infusion, in random order. Hormone pulses were tracked for 48 hours, and sleep was confirmed overnight with brain wave monitoring.
What they found
With the salt-water infusion, LH pulse frequency and average LH levels dropped significantly during sleep (P less than 0.01 for both). Naloxone did not change LH pulse frequency while awake, but it stopped the sleep-related drop and significantly increased LH pulse frequency during sleep (P less than 0.001).
What it means for you
This suggests the body's own opioid signals are at least partly responsible for slowing reproductive hormone pulses during sleep early in the cycle. This is a small, mechanistic lab study about hormone biology, not a treatment or symptom study, so it does not directly tell us about PMS or PMDD symptoms, and the sample was very small.
10
women studied
P<0.01
sleep-related LH drop with salt water
P<0.001
LH pulse increase with naloxone during sleep
About the study
- Original title
- Sleep-associated decrease in luteinizing hormone pulse frequency during the early follicular phase of the menstrual cycle: evidence for an opioidergic mechanism
- Authors
- Rossmanith WG, Yen SS
- Journal
- The Journal of clinical endocrinology and metabolism
- Year
- 1987
- Study design
- Randomised trial
- Participants
- 10
- What was tested
- Naloxone (an opioid-blocking drug) infusion compared with a salt-water infusion
- Read the paper
- doi.org/10.1210/jcem-65-4-715