As mbg previously reported, recent studies on valerian's effectiveness as a sleep aid have yielded mixed results. For every study that says taking valerian before bed can improve sleep quality and ease nighttime anxiousness, there is one that indicates it is not an effective sleep aid.
A systematic review of clinical research on the herb, published in 2000, concluded that there is "significant inconsistency in terms of participants, experimental design and methodology among the trials."
A 2006 systematic review, 2010 meta-analysis, and 2020 combination systematic review and meta-analysis further echo the many methodologic problems of valerian studies to date, even including publication bias, while suggesting valerian might modestly help with subjective sleep quality. The key word being "subjective," since objectively quantified data is lacking.
After reviewing the pool of existing research, the NIH declared that there is not enough evidence to determine the effectiveness of valerian to help with major sleep disturbances or issues. "Overall, the evidence from these trials for the sleep-promoting effects of valerian is inconclusive," the Institute notes.
Valerian has also been associated with a number of side effects, including a queasy stomach, abdominal cramps, restlessness, and agitation.
If you are someone who enjoys taking a supplement or sleep tea formulated with valerian and find that it helps you get better rest, by all means, continue. But if you're open to another option, there are other sleep supplements that might prove more reliable.