Why can't I get up in the morning?

Based on my personal experience, I can't get up in the morning if -- I couldn't fall asleep in the evening, I have excuses for not getting up in the morning, or I have to stay up to work

I sometimes feel the same way. Honestly, there might not even be a reason as to the question "why". Sometimes you might just be exhausted and other times you might not want to get up to do what you were going to do (school, work, etc) and that's completely okay! The stress everyone faces throughout the week is very draining physically and mentally, especially if you're in school or working. Every once and awhile everyone needs a break, whether that be mental break or physical break is up to you. However, everyone needs time to recoup and generate more energy. Sometimes my mental battery just wears out and I feel like I don't want to get up.