I've been doing exams the last week and didn't sleep very much the last 3-4 days. On Thursday I still trained quite good (long run) but yesterday I had to squat and do some arms exercises and I preferred to rest. An intense cardio workout would have been pretty much the same issue, I guees. So today I should be doing something. I suppose than running easy isn't a problem as far as I don't try to have the same pace than a normal day.
Probably I can handle it better than I suppose as I can sleep 7h, even 6,5, without any particular problem. Now I have been sleeping 4-5 xD. Does a short nap help? 30'?