We have studied the effect of vitamin B12 (VB12) on the sleep-wake rhythm following an 8-h advance of the light-dark (LD) cycle in the rat. The electroencephalogram and electromyogram were recorded on chart paper via a two-channel telemetry system. Infusion of VB12 (Mecobalamin; 0.25 microgram/h) or saline into the abdominal cavity was performed using an implanted miniosmotic pump. Before the phase shift, there was no significant difference between the two groups in terms of the mean daily amount of each vigilance stage. Following the phase advance, in the saline group, wake gradually decreased and nonrapid-eye-movement (NREM) sleep and REM sleep increased. In the VB12 group, no significant change was seen in any of the vigilance states, except for REM sleep on day 3. The results suggest that VB12 may maintain homeostasis of sleep and/or wake amount following an 8-h advance of the LD cycle in the rat.
Animals Circadian Rhythm