49 yo female suffering from migraines for 30 yrs. over the last 10 yrs, they have ocurred within the first 2 hrs of going to bed. i do not get them every night. they come in clusters & i can go anywhere from 9-15 months without a headache & then get them every night for up to 6 weeks. i am on depakote & calan to prevent them. MRI shows that i have bone spurs in my neck. i do see a neuro, chiro & get acupuncture. any ideas why they come at night?