I am only one in my class that sleeps in the afternoon after school is that ok?

It's a nap.: Naps by themselves are not generally harmful, but the question to be answered is: why do you need the nap in the first place? Sleep apnea? Medications? Depression? Just not enough sleep at night? The concern is not the nap, but why the need for the nap. That being said, napping during the day can disrupt your sleep at night, so try not to nap if you can.