Last weekend I was down about 6 hours, gained three hours in the first part of the week and was down two hours again last night. So I’ve a sleep debt of five hours.

Each weekend, I suppose I could pay four hours of sleep debt (to bed an hour early and get up an hour late– five hours if nothing fun is happening on Friday). At best, I can pay off an hour of sleep debt a day on a workday, and that only if nothing really is going on– just gym, eat, sleep and minor errands.

So 9 hours a week of sleeping in can pay back the maximum sleep debt of 20 hours in about 2 weeks, which seems low compared to other estimates of several months.