"I go to sleep at around ten thirty p.m."
It's not exactly the same. ます is the polite conjugation that can indicate present or future tense. います is a conjugation that indicates ongoing activity at the moment.
Here, the plain form of the verb is ねる (寝る) 'to go to sleep.' ねます is 'I (will) go to sleep' where ねいます is 'I am sleeping.'