Patterns of diel activity—how animals allocate their activity throughout the 24-h daily cycle—
play key roles in shaping the internal physiology of an animal and its relationship with the …

Many animals regulate their activity over a 24-h sleep–wake cycle, concentrating their peak
periods of activity to coincide with the hours of daylight, darkness, or twilight, or using …

Examples are presented of nocturnal animals becoming diurnal or vice versa as a result of
mutations, genetic manipulations, or brain lesions. Understanding these cases could give …

Mammalian life shows huge diversity, but most groups remain nocturnal in their activity
pattern. A key unresolved question is whether mammal species that have diversified into …

In mammals, light input from the retina entrains central circadian oscillators located in the
suprachiasmatic nuclei (SCN). The phase of circadian activity rhythms with respect to the …

Nocturnality is a key evolutionary innovation of mammals that enables mammals to occupy
relatively empty nocturnal niches. Invasion of ancestral mammals into nocturnality has long …

Most modern mammals, including strictly diurnal species, exhibit sensory adaptations to
nocturnal activity that are thought to be the result of a prolonged nocturnal phase or …

Circadian clocks predictively adjust the physiology of organisms to the day/night cycle. The
retina has its own clock, and many diurnal changes in its physiology have been reported …

Diurnality, associated with enhanced visual acuity and color vision, is typical of most modern
Primates. However, it remains a matter of debate when and how many times primates re …

The locomotor activity rhythms of domestic mice, laboratory rats, Syrian hamsters, Siberian
hamsters, Mongolian gerbils, degus, and Nile grass rats were compared. Running-wheel …