I'd be suprised if your room is 22c all day and all night. These fish come from large rivers with stable temperatures so they wont take the variable temperature of an unheated tank well, however its your fish so your choice.
Well, I dunno.
It's pretty toasty in here
I've got 3 fish tanks heated to 27C, and the central heating is permanently on with a vent under my bed.
I have double-glazed windows which are always closed and about 5 inches of insulation above my ceiling.
I really don't know whether the temperature dips significantly as there is no thermometer in my room.