Meanwhile, SAMe builds up. Serotonin levels follow roughly the same pattern-higher during the day and lower at night. It appears that the serotonin synthesized during the day is used at night to make melatonin. SAMe is absolutely crucial for the natural synthesis of melatonin because it donates a methyl group molecule to the enzyme that converts the acetylated form of serotonin to melatonin. This normally occurs as the sun goes down.
Beta blockers are a class of drugs used to treat heart problems.
People who take beta blockers to block beta receptors in their heart, block receptors in their brains as well. Blocking neal receptors interferes with the synthesis of melatonin. The extent of the disruption caused by beta blockers to circadian rhythms, and the important hormones that depend on these rhythms, was illustrated by an animal study showing that ingesting a beta blocker before bedtime is like leaving the lights on all night. What occurs when beta blockers are taken before bedtime looks a lot like sleep deprivation. Medica Scandinavia clearly demonstrates the melatonin-disrupting effects of beta blockers.