I wonder how some people manage to be energetic all day long on only 4-5 hours of sleep. Even if I sleep for nearly 7 hours, I still struggle to rise when the alarm clock goes off, and I become quite sleepy the next day, especially in the afternoon. A miserable morning can make the whole day feel miserable. So that I might be less run down when I wake up, I decided last night to try going to bed at 22:30 to ensure myself 8 hours of sleep. This morning I did indeed wake up with more energy than usual, and I did not become sleepy during the day. So I would like to stick with this routine to see if it remains helpful. "I decided last night ... at 22:30" sounds better than "I decided... at 22:30 last night" because "last night" more naturally modifies "decided". Keep adverb phrases next to the words they modify, when possible. Note the preposition "on" in the first sentence. We can be energetic "on" 4-5 hours of sleep in the same way that a car can travel 100 miles "on" 3 gallons of gasoline.

I wonder why/how some people can remain energetic all day with only 4-5 hours of sleep. Even if I sleep for nearly 7 hours, I still struggle to get up when the alarm clock goes off and I become quite sleepy during the day (here, the next day means the day after this one), especially in the afternoon. A miserable morning makes the whole day feel miserable. In order to make my mornings less painful when I wake up, I decided to go to bed at 22:30 last night to ensure that I get 8 hours of sleep. When I woke up this morning, I felt more energetic than usual, and I didn’t get sleepy during the daytime. So, I would like to stick to this routine to see whether it is helpful or not.