Well, because if you are having pain only intermittently -- it may be only pinched or compressed slightly -- and a movement that irritates the nerve, can cause it to become inflammed -- and cause the pain to occur for several weeks to months.
And people with nerve compression problems often have it worse at night, because during sleep -- your body does toss and turn into weird positions and could be putting more pressure on it. (Classically, the nerve compression in carpal tunnel - a related condition - wakes people up at night).
So, because you have been having this for 8 years, it may make sense to have this evaluted.
MRI of the cervical spine can be done.
EMG/nerve conduction testing can be done.
Neurology referral can help with a thorough neurologic examination.
Of course, if it isn't bothering you too much, then you can watch and wait.