My two also chase each other around the flat like crazy and they do this twice a day, at 7 in the morning (my poor downstairs neighbors!) and at 10 in the evening. Guess they all need to burn down energy!
The daily routine, when I come home from work every morning. The cats greet each other like they're meeting for the first time, and then treat me like I've been away for months, and then settle down into Tranquility Mode, before getting a case of the Crazies and burning off the energy of 18 hours of sleep.