If biphasic sleeping was normalized again, what would you do in those few hours between sleeps?

I once had the perfect job for biphasic sleeping. I would get up at 4 AM, work and be home by about 1 PM, sleep til 4 PM, stay up til 11 PM, then back to bed til 4 AM. 8 hours of sleep a day, 7 or 8 hours for work, 7 hours in the afternoon and evening for whatever I wanted, and I felt well-rested the whole time. It's the only thing I miss about that job.