Physical tiredness does not create sleepiness. Sleepiness is a mental condition. Physical tiredness does not cause the mind to go to want to go to sleep. The mind can be sleepy but the body can be energized and interfere with going to sleep.

Sleepiness is a result of a body rhythm. It restores the brain.
Tiredness is the result of physical activity. It restores the muscles, etc. during sleep.

Any kind of active thinking will get in the way of falling asleep. Foam earplugs can help you ignore or not get stuck thinking about the noises from roommates. A "What was that noise?" mental question can be a problem. Often, it helps to get up and see what the odd noise was so the mind can let go of that question.

A note pad can be helpful. Write down all of your end of the day thoughts that may need addressing the next day. This can help the mind let go of the thought.

Classic sleep hygiene is a foundation for getting to sleep but this extra step of helping the mind let go is important and is a struggle specific to PCS.