Hypnic headache is a rare, primary headache disorder (primary headache disorders are those that cannot be attributed to another condition). Its most unique feature is that it ONLY develops during sleep and wakes the sufferer, which is why it has also been called “alarm clock’ headache.
People with new or never-evaluated hypnic headache should be carefully assessed by their doctor to:
- Ensure there is no underlying secondary causes for the headache. Some examples include intracranial disorder causing high intracranial pressure, sleep apnoea, nocturnal high blood pressure, nocturnal low blood sugar and medication withdrawal (i.e. as the pain medication wears-off overnight a headache breaks through); or
- To make sure that they do not have a different primary headache disorder that can mimic hypnic headache. Examples of primary headache disorders that can occur from sleep include cluster headache and migraine headache.
Hypnic headaches are frequently occurring headaches (occur on greater than 10 days per month) that happen only during sleep. The headache will last between 15 minutes to 4 hours after waking. Often hypnic headaches begin in people after age 50 years, but may occur in younger people as well. The pain can range from mild to severe and is usually bilateral (on both sides of the head). Sometimes people may describe migraine-like symptoms including nausea with hypnic headaches.
Please refer to the International Classification of Headache Disorders 3rd edition (beta version) website for more information on the criteria used to diagnosis hypnic headache: https://www.ichd-3.org/other-primary-headache-disorders/4-9-hypnic-headache/
Bedtime doses of caffeine is the most commonly used treatment. For most patients, paradoxically, caffeine does not prevent patients from sleeping adequately. Melatonin, flunarizine, and indomethacin have been shown effective in some cases.
Lithium carbonate can be used to stop hypnic headache, but must be used with caution especially in the presence of kidney disease, thyroid disease, dehydration, or use of diuretics.
Some case studies have shown daily preventive use of topiramate also to be effective.
Hypnic headache is rare, and should be diagnosed only after other causes have been ruled out. Hypnic headache begins during sleep and wakes the sufferer, then generally lasts 15 to 180 minutes. Lithium carbonate, caffeine, melatonin, flunarizine, indomethacin, and topiramate have been successful in treating hypnic headache.
The International Headache Society. https://www.ichd-3.org/other-primary-headache-disorders/4-9-hypnic-headache/
Holle D, Naegel S, Obermann M. Hypnic headache. Cephalalgia 2013; 33:1349.
Liang JF, Wang SJ. Hypnic headache: a review of clinical features, therapeutic options and outcomes. Cephalalgia 2014; 34:795