How activity signals affect the main body clock differently in night-active and day-active mammals

The light responsiveness of the suprachiasmatic nucleus (SCN) is maximal during the night in both nocturnal and diurnal species.

• The SCN regulates sleep and wake patterns based on environmental light cues.
• Behavioural arousal during resting periods can disrupt sleep and influence circadian rhythms.
• Different species exhibit varied sensitivity to arousal during sleep, affecting their internal clocks.
• Arousing stimuli can reduce light resetting in nocturnal animals while increasing it in diurnal animals.
• Further study is needed on circadian disruptions linked to shift work and trans-meridian travel in both nocturnal and diurnal species.

Simplified