I take 40mg nortriptyline before bed. however it's like a energy buzz. i'm wide awake all night. day i'm fatigue. lack energy & strength. this normal?

Not really: Most people find that nortriptyline makes them sleepy. It's not bad that you're having these side effects; it just might not be the right medication for you. You might want to move it to the daytime and see if that works better for you. I don't know why you are taking it and that would make a difference if you could change to something with less side effects.