Hypnic headache (HH) is a rare primary headache disorder (primary headache disorders are those that cannot be attributed to another condition.) The most recognizable feature of hypnic headache is that it only develops during sleep and wakes the sufferer.
Characteristics of HH:
- The headache occurs at a consistent time each night, usually between 1 and 3 a.m.
- The pain is usually mild to moderate, but can be severe.
- The first occurrence of HH is typically after the age of 50, although more data shows the age of onset to usually be between the ages of 40 and 82.
- The pain of HH is bilateral in approximately 66% of cases.
- HH develops during sleep and awakens the sufferer.
- The duration of HH is usually 15 to 180 minutes.
- The symptoms of include only ONE of the following:
Before arriving at a diagnosis of hypnic headache, imaging studies should be performed to rule out any organic issues.
- Lithium carbonate, 300 mg at bedtime, is frequently used to treat HH, but it must be used with caution especially in the presence of renal disease, dehydration, or use of diuretics.
- Doses of caffeine, flunarizine (a calcium channel blocker), and indomethacin at bedtime have been shown effective in some cases.
- There have been some case studies of HH that have shown daily preventive use of topiramate (Topamax) to be effective in some cases.
The International Headache Society’s International Classification of Headache Disorders, 2nd Edition (ICHD-II), is the “gold standard” for diagnosing and classifying headache disorders. Here are the description, diagnostic criteria, and symptoms of HH as set forth in the ICHD-II:
4.5 Hypnic headache
Previously used terms: Hypnic headache syndrome, ‘alarm clock’ headache
Description: Attacks of dull headache that always awaken the patient from asleep.
- Dull headache fulfilling criteria B–D
- Develops only during sleep, and awakens patient
- At least two of the following characteristics:
- occurs 15 or more times per month
- lasts 15 or more minutes after waking
- first occurs after age of 50 years
- No autonomic symptoms and no more than one of nausea, photophobia or phonophobia
E. Not attributed to another disorder1
1 Intracranial disorders must be excluded. Distinction from one of the trigeminal autonomic cephalalgias is necessary for effective management.
The pain of hypnic headache is usually mild to moderate, but severe pain is reported by approximately 20% of patients. Pain is bilateral in about two-thirds of cases. The attack usually lasts from 15 to 180 minutes, but longer durations have been described. Caffeine and lithium have been effective treatments in several reported cases.
Wrapping it up:
Hypnic headache is rare, and it should be diagnosed only after any organic, physical causes have been ruled out with imaging studies. HH always begins during sleep and wakes the suffer. HH usually lasts from 15 to 180 minutes. Lithium carbonate, caffeine, flunarizine, indomethacin, and Topamax have been successful in treating HH in some cases.