I'd probly have to say 22.5 hours are sleeping. But I'm not sure what they do deep into the night. I woke up this morning to see Monty cruising around his cage, maybe they are more active then we think.
LOL HOOMI...
I would say that they spend 5-6 hours cruising around their cage off and on throughout the night. I monitor mine sometimes when I am up to all hours of the night, and they usually "wake up" or "become active" around 8-9pm and don't stop until about 12-1am. Then they rest a bit, come back out from about 5-7am. But then of course we can't forget about when they are hungry and restless, taking a swig, moving from cold end to warm end, etc. throughout the day that we don't see. So in other words- who really knows?? LOL