18 y/o male had 2 sleep studies, first one they gave me a sleep pill, indicated i had osa. i am worried about them being accurate cuz i didn't sleep long?

Probably fine: You only need to collect 4 hours of good data to evaluate oxygenation, pulse, chest/abdomen/limb movements, and mouth vs. Nose breathing during a sleep study. Chances are good that if you took a sleeping pill for the sleep test and collected a few hours of sleep data, you should get some useable information.

Sleep problem: A sleep study can be done with very little sleep. If you have obstructive sleep apnea it is something that should be treated. Start by losing weight, and either a dentist trained in dental sleep medicine or a sleep phycisian can help. I am biased towards a dentist because an oral appliance is comftorable and easy to use.