I've commuted by bike at any hour you can name at various jobs.... night, swing, and day shifts. Currently multi-mode commute with the help of transit, so my bike commute varies between 3 and 24 miles round trip. I prefer maxing out on the ride home as traffic is so much less after 8PM. Getting hard to ride in the morning due to increasing arthritis in one knee, will probably have to do something about that soon.