Acute increases in night-time plasma melatonin levels following a period of meditation

To determine whether a period of meditation could influence melatonin level s, two groups of meditators were tested in a repeated measures design for c hanges in plasma melatonin levels at midnight. Experienced meditators pract ising either TM-Sidhi or another internationally well known form of yoga sh owed significantly higher plasma melatonin levels in the period immediately following meditation compared with the same period at the same time on a c ontrol night. It is concluded that meditation, at least in the two forms st udied here, can affect plasma melatonin levels. It remains to be determined whether this is achieved through decreased hepatic metabolism of the hormo ne or via a direct effect on pineal physiology. Either way, facilitation of higher physiological melatonin levels at appropriate times of day might be one avenue through which the claimed health promoting effects of meditatio n occur. (C) 2000 Elsevier Science B.V. All rights reserved.