Ideally you would mirror the daylight times of Australia, although without an expensive programmable timer, this won’t be practical. Instead, the basic setup is 12 hours on, 12 hours off for both UVB and the basking spot light bulb.
With a constant background temperature and lighting period, this tends not to stimulate brumation (hibernation) in the bearded dragon.
If you want to match the lighting cycle more closely and stimulate brumation and breeding behaviours then I recommend using the following lighting schedule for both the UVB and basking spot:
Spring: 12 hours
Summer: 14 hours
Autumn: 12 hours
Winter: 10 hours
For the winter time, you may also want to cool down the tanks basking spot temperature a bit for more natural climates by about 10°C/ 24°F (29°C/ 80°F instead of a normal 40°C/104°F). This kind of temperate drop only needs to happen for 4-6 weeks and ideally this kind of change should be gradual.
However, most of our homes naturally get colder anyway and so will produce this effect anyway, providing the temperature drop isn’t too severe (minimum 16°C / 60°F at night). If you use supplemental heating to provide a constant background temperature, then you may want to lower this for winter slightly.
In hotter times in the summer we’ll turn off the basking spot for a while during the day, up to 6 hours off – depending also on if we take them outside to bask in the summer sun. Remember that they need the heat to aid digestion and metabolism, but a good sign of overheating is constant gaping (mouth open) while in the cooler end of the tank.
Remember, between every 6 to 9 months you need to change your UVB light source.
Best UVB Bulb for Bearded Dragons