Turned on by everything??

My boyfriend is literally turned on by everything. He loves having sex, and I do to but sometimes I just want to cuddle or sleep with him (actually sleep) & we can for a little while and then he's hard (or hard again if we already had sex.) Sometimes I just don't know how sleeping or cuddling can turn someone on?? Sometimes I feel like he wants sex too much especially when he's turned on by things like this but he's probably just being a guy right? Is anyone else's man like this or should I be concerned?