If you've ever heard a choir of crickets begin to chirp as the sun sets, you've experienced firsthand an example of nature's circadian rhythm. Plants and animals -- including humans -- have an internal daily clock that helps to govern behavior and activity and also controls other physiological processes, like blood pressure and urine production. Many compounds within your body help to regulate your internal daily clock, including vitamin B-12 and the hormone melatonin.
Function of Melatonin
In its role as a brain hormone, melatonin has an effect on your natural sleep-wake cycle. In the absence of light, a hormone-secreting gland within your brain releases melatonin, which in turn triggers feelings of sleepiness to aid in slumber. In addition to contributing to your internal clock, melatonin also controls the release of other hormones in your body, particularly hormones associated with the female reproductive system.
Vitamin B-12, Circadian Rhythm and Melatonin
Vitamin B-12 also plays a role in regulating your internal clock and circadian rhythm. Every morning, the presence of light stimulates your brain to induce feelings of alertness, which helps you to wake up and start your day. The presence of vitamin B-12 helps boost the response to external light and turn off melatonin signaling in your brain, helping your brain make the transition from a resting sleep state to a more active awake state.
Vitamin B-12 and Melatonin for Sleep
Due to its effect on melatonin and on sleep-wake cycles, vitamin B-12 has been implicated in sleep disorders. A study published in "Neuropsychopharmacology" in November 1996 found that methylcobalamin vitamin B-12 supplements could increase alertness at night, aiding in sleep reduction and the capacity for activity at night. Taking supplements containing methylcobalamin at night might alter your sleep cycle. If you take the supplements over a long period, you might develop sleep deprivation.
Vitamin B-12, Melatonin and Jet Lag
You may notice the powerful effect of your body's normal circadian rhythm when you travel to another time zone and realize the difference between your biological and the local clock, a phenomenon known as "jet lag." Because of its ability to induce wakefulness and increase sensitivity to light, vitamin B-12 might help your body shift your internal clock and adjust to your new time zone. However, upon returning back home, you will likely again experience jet lag, as your body must readjust to your regular time zone.
- University of Maryland Medical Center: Melatonin
- "Neuroscience Letters"; Vitamin B12 Enhances the Phase-Response of Circadian Melatonin Rhythm to a Single Bright Light Exposure in Humans; S. Hashimoto, et al.; December 1996
- "Neuropsychopharmacology"; Effects of Vitamin B12 on Performance and Circadian Rhythm in Normal Subjects; G. Mayer, et al.; November 1996
- "Brain Research"; Methylcobalamin Amplifies Melatonin-Induced Circadian Phase Shifts by Facilitation of Melatonin Synthesis in the Rat Pineal Gland; M. Ikeda, et al.; June 1998