Melatonin has been shown to accelerate the adaptation of the circadian system to a night work schedule.

The same may be true for the circadian system.

People with normal circadian systems can generally fall asleep quickly at night if they slept too little the night before.

So we came up with this idea: Mom is functioning as the transducer for the fetal circadian system.

Mom's melatonin rhythm is a very precise marker of her circadian system.

Before the mid-1980s, it was believed that only eukaryotes had circadian systems.

Daylight also has the correct intensity and spectrum needed to stimulate the circadian systems.

However, classroom lighting may also have an impact on students' circadian systems, which may in turn affect test scores, attendance and behavior.

Whether they are larks or owls, people with normal circadian systems:

"If this is the case, these patients may respond best to drugs that modify the circadian system."