I also get hypnic headaches. I find that mine can be seasonal. They seem to get worse when the amount of sunlight gets less. My opinion is that it has something to do, then, with melatonin. When mine ramp up again in the fall of the year, I take melatonin. Currently I’m taking 5 mg. of melatonin. I have gradually gone up to 15 mg. in the past with my neurologist’s blessing. I also take gabapentin. I also adjust that slightly up or down depending on my needs. Sometimes a strong 1/2 cup of coffee before bed also helps. Don’t expect a lot of help from your neurologist. These headaches are rare and they likely have not treated many patients with them. Best of luck to you. These headaches are miserable.