Bearded dragon experience day and night cycle, which is called the photoperiod. The photoperiod duration on day and night is depends on the season.
In the wild, the photoperiod duration of bearded dragon varies with the season. It might be 14 hours day and 10 hours night for summer or 10 hours day time and 14 hours night time for the winter. Spring is the time with 12 hours day and night. In captivity the bearded dragon is doing well with the 12 hours day and night.
To have an appropriate photoperiod for bearded dragon, an economical way is to switch on and off the lights manually. You will to remember to do this everyday and it will be very tiring. A better way is to use a timer for the lighting. It can be done automatically with the timer. However, do not take it for granted and do a check on this from time to time.
A healthy living of bearded dragon may largely depend on the surrounding environment. This includes the correct setting of photoperiod for your reptile pet.