Some problems become easier when I'm sleepy because I can't think as clearly but I start to focus very well. Other problems demand several passes of experiment

Some problems become easier when I'm sleepy because I can't think as clearly but I start to focus very well. Other problems demand several passes of experimentation. For those it's easier to try a quick test during the day, think about it while doing other things, and then wake up with the (possible) solution the next day.