Your day is entirely what you make it.
At DMU, lecture material is posted online, as well as MP3's/Videos of the actual presentations, so if you want to wake up whenever, study at your leisure, you're able to do so.
At the same time, if you want to get any sort of human contact from the people in your field, it would behoove you to attend classes (generally 4-5 hours/day depending on the course load).
This is also entirely dependent upon where you are in the program. As you progress, you'll need to attend more and more for interactive things, like biomechanics/anatomy and the like, but I basically attended no actual classes the entire first year. I'm not lazy, far from it, I just found it pointless to attend lectures that contained extremely dense material that I would be lost in about 10 minutes in, and found my time better spent going over the material at my own pace, making study materials as I went. No sense in seeing the same material twice if you didn't understand anything the first time.
By and large, during intensive points in the program, I'd spend 40-60 hours/week doing school related studying/reviewing, and had no problem making the grades. Some weeks require less, some more, but it's tough to generalize an "average" day when courses are in blocks and some are far easier than others.
You'll spend a lot more time studying than you did in undergrad (or the exact same amount but with lower grades). The running joke my first year was if we'd put in the effort required here in undergrad, we'd all have had a 4.0, easily.
