I usually fall asleep when I study or read for over an hour. However, today, I studied for one and a half hours before falling asleep. I feel excited about that improvement because I now know I can study and read for a longer time. Pay attention to the difference between "learn" and "study". You only learn something if it lodges itself inside your brain and becomes part of what you know. You can say you "studied an hour", "were studying an hour", or were learning an hour" but it seems slightly odd to say you "learned for an hour".

I usually fall asleep after studying or reading for over an hour. However, today, I learnt for one and a half hour before I fell asleep. I felt excited about that because I understood that I could learn more and read for a longer time.

I usually fall asleep when I have been studying or reading for over an hour. However, today, I learnt for one and a half hours before I fell asleep. I felt excited about that because I know I can stay awake longer to learn more and read for a longer time.