Genuinely would like others thoughts on this.

The other night - as always woke up early hours to go toilet, come back in the room not realising he was awake and he screams AHHH at me.
Me obviously being scared by it he finds it hilarious yet i end up with a sleepless night from nightmares and struggling to sleep.

He constantly does stuff like this - sneaking up behind me to make me jump.

I don't think i'm over reacting as i scream every time, i'm a very anxiety high and shaky person so it really upsets me but he just goes its a joke its funny.
Other people find it funny why cant you.

Maybe because your genuinely causing me fear thinking someone broke in ffs.

Thoughts? Is this a joke or is what i'm feeling valid because i'm sick of it every other day.