The rhythm is linked to the light-dark cycle.

Recent research has influenced the design of spacecraft environments, as systems that mimic the light-dark cycle have been found to be highly beneficial to astronauts.

Normally however, external cues like light-dark cycles and social interactions also exert an influence on the body's rhythms.

In 1999, Russell G. Foster showed that entrainment of mice to a light-dark cycle was maintained in the absence of rods and cones.

The resulting Drosophila exhibits arrhythmic activity and cannot entrain to any light-dark cycle.

This outcome is a logical consequence of the bimodal locomotor activity profile under a light-dark cycle.

This finding indicates that the mother, and her entrainment to surrounding light-dark cycles, must provide the necessary information to the fetus for synchronization.

Aschoff's work in the field of chronobiology introduced the idea that shifting one's light-dark cycle can result in harmful effects, such as correlations with mental illness.

Aschoff's parametric model states that entrainment occurs through gradual changes in the clock that adapt to a new light-dark cycle.

He found that the absence of a light-dark cycle does not prevent humans from entrainment.