Lichstein KL, Payne KL, Soeffing JP, Heith Durrence H, Taylor DJ, Riedel BW, Bush AJ. Vitamins and sleep: an exploratory study. Sleep Med. 2007 Dec;9(1):27-32. Epub 2007 Sep 6.
Honma K, Kohsaka M, Fukuda N, Morita N, Honma S. Effects of vitamin B12 on plasma melatonin rhythm in humans: increased light sensitivity phase-advances the circadian clock? Experientia. 1992 Aug 15;48(8):716-20.
Studies have shown a variety of results concerning the effect of vitamins on sleep patterns. One study from the University of Alabama had 772 people ranging from age 20 to 98 fill out questionnaires about their sleep habits, health, and general daytime functioning. A total of 519 of them took vitamins regularly. Participants completed the diaries for 2 weeks. The results showed that those who took multivitamins or multiple single vitamins had poorer sleep as compared to those who did not take vitamins. Vitamin takers generally awakened more often during the night and were awake longer. The researchers controlled for gender, age, and ethnicity and the results persisted. Several possible explanations include:
- Vitamins cause poorer sleep
- Poor sleepers are more likely to use vitamins
- Unidentified factors associate vitamin use and poor sleep.
The second study, from Japan, showed that vitamin B12 use affected melatonin levels and promoted wakefulness in study participants. However, total sleep time was not affected, suggesting that B12 use simply shifted circadian rhythms and increased light sensitivity, rather than changed overall sleep hours.
Those who suspect vitamin use may be disrupting their sleep may wish to try taking vitamins several hours before bed, or in the morning.