Hi Margeaux, Very interesting question. I would say that it is a physical influence, especially since it often changes as we age. Teenagers, for example, learn best in the afternoon or evening. Younger children and many adults in the a.m. People can of course learn to adapt to learning at different times of day but as with learning styles, they usually have a preferred time of day to learn. I find that with my adult learners who are primarily evening students, many having worked all day, that I need to take frequent breaks and use interactive exercises to keep everyone awake and alert. Best wishes for continued success in your teaching career. Susan Susan Polick