Im on a new anti dppressant can someone explain why if its prescribed to help me sleep does it make me wired?

The name of it is amitriptyline or common brand Elavil. I dunno but my dr. Said itll help me sleep but really I was wired and severely sensitive to the cold today... Im also on effexor xr which ive been on for 6 years... Is the pill making me this way?