Vitamin B-12 deficiencies can cause dementia, psychosis and mood disturbances. These symptoms can appear in some people when their B-12 levels are only slightly lower than normal and well above those considered indicative of anemia. Because disturbed sleep is a common symptom of disorders that are known to involve B-12 deficiencies, some researchers have studied whether or not supplemental vitamin B-12 would improve sleep.
Different Forms of Vitamin B12 and Sleep
A few studies have shown improvements in sleep in response to vitamin B-12 supplementation. In a 1996 study published in "Neuropsychopharmacology," researchers reported differences in the way research subjects responded to either cyanocobalamin or methylcobalamin, which are different forms of vitamin B-12. Methylcobalamin significantly reduced sleep time, and subjects taking this form of the vitamin reported having good quality sleep and feeling more refreshed after taking the vitamin.
Increased Sensitivity to Light
Your internal circadian rhythm is sensitive to light. This is the reason that winter darkness will often disrupt those rhythms and lead to depression. In a 1992 article published in "Experentia," researchers found that subjects given vitamin B-12 had lower average melatonin levels. Furthermore, they had lower levels of melatonin when exposed to light than did subjects not given the vitamin. Supplementation did not, however, affect the timing of sleep. The researchers concluded that vitamin B-12 advanced the human circadian rhythm by increasing sensitivity to light; however, other research has shown no effect at all of vitamin B-12 on circadian rhythms. The Mayo Clinic's information sheet on vitamin B-12 stated that the evidence for this effect is weak.
Delayed Sleep Phase Disorder
Some people have sleep onset insomnia and difficulty waking up at the desired time, a condition known as "delayed sleep phase disorder." According to a 2009 article in the "Turkish Journal of Psychiatry," vitamin B-12 has been used successfully to treat this condition. Other treatments include light therapy, melatonin or chronotherapy.
Infant Sleep and Crying
Low vitamin B-12 levels during pregnancy are linked to excessive infant crying, according to a study published in the April 2011 issue of "Early Human Development." In this study, women were recruited during the 12th week of pregnancy and asked to give a blood sample, which was assessed for folate and vitamin B-12. After their infants were born, the women were asked to complete questionnaires about infant crying. There was no association between infant crying and folate, but there was a definite correlation with vitamin B-12 levels. Researchers speculate that prenatal vitamin B-12 may play a role in the maturation of the sleep-wake cycle.
References
- "Experientia"; Effects of Vitamin B12 On Plasma Melatonin Rhythm in Humans: Increased Light Sensitity Phase-advances In the Circadian Clock? K. Honma, et al.; August 15, 1992
- "Turkish Journal of Psychiatry"; Delyed Sleep Phase Type Sleep Disorder and Chronotherapy; Hizli F. Gokben; Summer 2009
- "Neuropsychopharmacology"; Effects of Vitamin B12 on Performance and Circadian Rhythm in Normal Subjects; G. Mayer, et al.; November 1996
- "Early Human Development"; Maternal Vitamin B-12 and Folate Status Dring Pregnancy and Excessive Infant Crying; G. Geodhart, et al.; Aprl 2011
- Mayo Clinic: Vitamin B12
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