Intake of L-serine before bedtime prevents the delay of the circadian phase in real life.

Background: It has been shown in laboratory experiments using human subjects that ingestion of the non-essential amino acid L-serine before bedtime enhances the advance of circadian phase induced by light exposure the next morning. In the present study, we tested the effect of ingestion of L-serine before bedtime on circadian phase in real life and whether its effect depends on the initial circadian phase.

Methods: The subjects were 33 healthy male and female university students and they were divided into an L-serine group (n = 16) and a placebo group (n = 17).

l-Serine Enhances Light-Induced Circadian Phase Resetting in Mice and Humans.

The circadian clock is modulated by the timing of ingestion or food composition, but the effects of specific nutrients are poorly understood. We aimed to identify the amino acids that modulate the circadian clock and reset the light-induced circadian phase in mice and humans. Male CBA/N mice were orally administered 1 of 20 l-amino acids, and the circadian and light-induced phase shifts of wheel-running activity were analyzed.