I'm not sure if it's the sort of thing you could be fined for, but if you were near any of the hotels and security saw you they would probably tell you to move. They don't want it looking like they have homeless people sleeping on their beaches.

Besides that, yea, I guess I might not want to stay out there all night in case a shady person with ill intentions found me. The thing is that the beaches aren't patrolled at night. If you want to be adventurous then go for it. Otherwise, I say grab a blanket and a bottle of wine and go for a moonlit stroll and hang out for a while, but go back to your room to sleep.

I love sleeping outside too, but in my own backyard or somewhere that I know I'll be safe.

Is it legal to sleep on the beach in Aruba?

Well, as Toby said, the hotels don't like you "camping" out on their beaches. I guess it depends on where you are. The hotels won't make a stink about it if they tell you to go back to your room and you do. But they might very well call authorities if you refuse to move.

Wow, this attracted a lot of views about sleeping on beaches. I haven't really tried sleeping on a beach before so I don't know exactly what it feels like. Maybe I won't be sleeping at all because I must be alert for any person that might want to hurt me.

Yes I think it's not about beaches and Aruba, it's about you sleeping outside in the public place. It's not safe at all. If you insist on sleeping on the beach in Aruba (which is not your case), you'd better do it with some friends and not alone.