Photoperiod

From UroWiki

The photoperiod refers to the length of day for the uromastyx, which varies depending on time of year. It is very unatural to have a constant 12 (or 14) hours all year long, and this lack of seasons has been known to have negative effects on some lizards. It is generally agreed that the photoperiod should be shortened in the winter (for example, 10-12 hours as compared to 12-14 in the summer), especially to take into account the psychological factors involved in brumation, although it should have a stable photogradient all year round. The temperature should also be kept at the same level all year round, even if the photoperiod is shorter. You should bear in mind the length of the dusk and dawn period as well.

Need for a photoperiod

Many animals, particularly those which hibernate or brumate, base their seasonal activities around the photoperiod. Therefore the specific day length, and thus knowledge of the season of the year, is vital. A number of biological and behavioural changes are dependent on this knowledge. Together with temperature changes, changing the photoperiod correctly reduces stress and helps the uromastyx recharge its body and immune system for the coming year. The photoperiod may also provoke changes in the colour and vibrancy of the uromastyx' markings, as well as changes in sexual behaviour. However, you should generally only start using varying photoperiods for uromastyx which are at least 10-12 months old.