I'm extremely tired, but can't sleep because of my itchy nose. is this an allergic reaction?

Yes: Allergy symptoms like itchy nose, stuffy or runny nose can interfere with sleep and make you feel tired because of lack of good quality sleep.

Possibly: Itchiness, stuffiness and excessive drainage are usual allergy symptoms. Itchiness by itself could be just from a local irritation. If it is allergic, taking an antihistamine at night should help.

Yes: You most likely have allergic rhinitis.

Possibly: The itchy nose is a typical symptom for allergic reaction. There could be other causes of itchy nose.