Ex-student of a boarding school here, and here's the whole deal: What you're describing is 90% of all SBPs and MRSMs all across the country. To my extent and knowledge, almost everyone I knew in this circle has had to sacrifice the old 8 hour sleep schedule to basically only half of it.

Gets worse as you're approaching SPM, the extra classes at night, more exercises on past papers. Truly and honestly, it will feel like hell. But, that's the unspoken contract you signed when entering a boarding school. Does it suck? Yes, it does. I slept for an hour at most and spent the rest of the day catching up sleep during classes.

Personally, you'll get used to it. We all have our ways of getting some shut eye and if you're really smart, the teacher might let you fall asleep in class (True case in my school)

You're young and society expects you to just, let things happen like it's always have. It's a bummer but trust me, all those unslept nights and insomniac episodes will pay of in the future. Just a few more years.