I have been having excessive blinking could this be caused by a nervous tic tiredness anxiety or something life threatening i am 16?

Excessive blinking: Can be Fromm anxiety or fatigue as you mention. It MAY also be from a condition that causes the eyelids to spasms which can be diagnosed and treated by your doc. Please see him/her. It is unlikely to be anything life threatening. If anxiety, a mental health professional can teach you some stress management. Peace and good health.

May be due to nerves: There are several causes of eye blinking and yes being nervous can be one. Others would be allergies or eye irritation. Less likely would be a tic if you are just now getting this symptom because tics usually start at a younger age and last for several months. If you notice your eyes are red or sore please see your doctor for an exam. Here is a helpful link http://www.healthgrades.com/symptoms/eye-blinking-symptoms