With only 80 documented cases, hypnic headache (HH) is one of the rarest headache disorders. HH is primary headache disorder, which means that it cannot be attributed to another condition.

The most identifying feature of HH is that it develops only during sleep and wakes the sufferer.

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.

Diagnostic criteria:

1. Dull headache fulfilling criteria B–D
2. Develops only during sleep, and awakens patient
3. At least two of the following characteristics:
   1. occurs 15 or more times per month
   2. lasts 15 or more minutes after waking
   3. first occurs after age of 50 years
4. No autonomic symptoms and no more than one of nausea, photophobia or phonophobia

E. Not attributed to another disorder¹

Note:
¹ Intracranial disorders must be excluded. Distinction from one of the trigeminal autonomic cephalalgias is necessary for effective management.

Comments:
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.

What does it all mean?

Characteristics of HH:

• Pain is usually mild to moderate, but sometimes severe.
• Develops during sleep and awakens the sufferer.
• Usually lasts 15 to 180 minutes.
• Symptoms include only ONE of nausea, photophobia (sensitivity to light), and phonophobia (sensitivity to sound).
• Usually occurs first after the age of 50, although more data shows the age of onset to usually be between the ages of 40 and 82.
• Headache occurs at a consistent time each night, usually between 1 and 3 a.m.
   

Diagnosis of HH:

Before assigning a diagnosis of hypnic headache, imaging studies should be performed to rule out any organic issues.
 

Treatment of HH:
Lithium carbonate, 300 mg at bedtime, is frequently used to stop HH, but must be used with caution especially in the presence of renal disease, dehydration, or use of diuretics.

Bedtime doses of caffeine, flunarizine (a calcium channel blocker), and indomethacin have been shown effective in some cases.

Some case studies have shown daily preventive use of topiramate (Topamax) also to be effective in some cases.
 

Summary:
Hypnic headache is very rare, and should be diagnosed only after any organic, physical causes have been ruled out. HH begins during sleep and wakes the suffer, then generally lasts 15 to 180 minutes. Lithium carbonate, caffeine, flunarizine,  indomethacin, and Topamax have been successful in treating HH.
 

____________
Resources:

The International Headache Society. "International Classification of Headache Disorders, 2nd Edition." Cephalalgia, Volume 24 Issue s1. May, 2004. doi:10.1111/j.1468-2982.2003.00823.x

Silberstein, Stephen D.; Lipton, Richard B.; "Goadsby, Peter J. Headache in Clinical Practice, Second Edition." Martin Dunitz, Ltd. 2002.
 

© Teri Robert, 2009 - Present.
Last updated November 29, 2010.

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