Glossary
Photoperiod
The daily cycle of light and dark hours an enclosure follows, usually set with a timer to mimic natural seasonal daylight.
Photoperiod refers to the number of hours of light and darkness an enclosure gets each day, which many reptiles use as a cue for normal daily activity as well as seasonal behavior, since day length in the wild shifts gradually across the year. A stable, appropriate photoperiod supports normal appetite and activity, while an erratic one, such as lights left on around the clock, can disrupt normal rest and behavior patterns.
Most keepers set photoperiod with a simple timer on the lighting circuit, running lights for roughly twelve hours a day as a general baseline and adjusting slightly to mimic seasonal changes for species where that matters, such as those that may brumate in the wild during shorter winter days. UVB bulbs are typically run on the same schedule as visible light, since the two occur together naturally.
A common mistake is running lights continuously with no dark period at all, which removes the day and night cycle an animal would otherwise rely on and can lead to stress or disrupted activity patterns. Another is changing the schedule inconsistently from day to day rather than using a timer, which makes the cycle unpredictable in a way that natural daylight never is.