Do you feel nauseous in the mornings?
Are you experiencing jerky, unsteady, motion of the trunk or the limbs?
Have you noticed that coughing, sneezing, straining, lifting make worse this type of headache?
Have you find ringing sensation in one of your ears?

I don't have any of the things you mention other than the ringing sensation in my left ear - not sure if I would call it ringing noise but there is a noise.

Have you noticed a hearing loss in the left ear, too?
Do you sometimes experience vertigo (an abnormal sensation of movement)?
Do you have pain in the face or left ear?

My hearing seems ok. I have experienced a little vertigo on occasion, and sometimes have a little pain on the left side of my face and my ear has a sensation of warmth.

Sounds like you might be having rebound headaches. Check out:
http://www.mayoclinic.com/health/rebound-h eadaches/DS00613

I have suffered severe headaches for the last 10 years or so. I was in my mid 30's then and had not had a history of headaches in my youth. It always seemed to be either 3 to 4 am in the morning that i would wake up and feel either a headache coming on or a bad one already there. The pain is always centred above my left eye.
3 months or so ago i felt bad pain in my teeth and when i went to the Dentist they discovered that i had a root canal infection in my tooth which is in my left top side of my teeth. I got the root canal work done and i noticed an almost immediate drop in the severity of the headaches. I asked my Doctor who said that the pain in my temple could easily have been caused by a festering infection in my teeth - we just had never considered the possibility - by the way, when the tooth was sore, it was always worse when i lay down which might mean a link to sleeping then the onset early in the morning each day SO - i would get your Dentist to do x rays of your gums/teeth to make sure it isnt the early stages of root infection which may be giving you the headaches.

Your symptoms can be due to an acoustic neuroma, benign, slowly growing tumor of the nerve that connects the ear to the brain (auditory) nerve.
The most useful (sensitive and specific) test to identify acoustic neuroma is an MRI of the head.