Beta blockers are a class of high blood pressure medications that have been around for decades. It is well known that beta blockers can disrupt sleep, possibly contribute to nightmares, and cause daytime fatigue. Beta blockers (along with non-steroidal anti-inflammatory medications) can reduce melatonin secretion, the hormone that is produced at night to help us sleep.
In the October edition of the Journal Sleep is a study about melatonin use in patients with high blood pressure on chronic beta blocker use. This study was a randomized, placebo controlled double blinded assessment. Patients' sleep was measured objectively in a sleep lab and at home for 3 weeks wtih actigraphy. Results showed statistically significant improvement in total sleep time, sleep efficiency, and onset to sleep with the melatonin in the sleep lab and at home. There was no sign of tolerance or side effects to the melatonin, or rebound sleep problems after stopping the melatonin.
These results are promising, as many patients need to take beta blockers for their long term cardiovascular health. Since this study was only three weeks long, we don't know the long term effects of melatonin use, so caution is warranted. Also, getting quality is difficult, since the FDA does not regulate the production of melatonin.