Background: The benefits of meditation are well documented, but the biochemical mechanisms have not been fully identified. One effect mechanism may be via influence on neurotransmitters.

Material and methods: Therefore, plasma melatonin and blood serotonin concentrations were measured before and after 1 hour of meditation in advanced male meditators (n = 27, mean age 46 years). They were compared with a matched reference group (n = 29, mean age 43 years) who rested for 1 hour. In the meditators, melatonin, and serotonin from before and after three consecutive hours of meditation were also compared.

Results: Initially, the median melatonin level was 4.9 pg per milliliter in the meditators and 3.1 pg per milliliter in the reference group (P < .01). After 1 hour of practice, melatonin had decreased to a median of 3.4 pg per milliliter in the meditators (P < .0001), but was unchanged in the reference group. After 3 hours of meditation, melatonin had declined further in the meditators. After 1 hour of practice, serotonin concentrations decreased in both the meditators and the reference group (P < .01).

Conclusions: The findings suggest that advanced meditators have higher melatonin levels than nonmeditators. Melatonin decreases during long meditation, a finding the study does not explain. Serotonin declines after both 1-hour meditation and rest, indicating that serotonin may be a marker of general rest and not meditation-specific relaxation.

Comments: Many small studies have evaluated the effects of melatonin on cluster and migraine. Here the authors summarize a relationship of melatonin, serotonin, meditation, and rest (the latter two variables clearly helpful in migraine). Does this help to explain why migraine tends to remit in sleep? Stewart J. Tepper