Cephalalgia. 2013 Jul 5.

Hypnic headache.
Holle D, Naegel S, Obermann M.
SourceDepartment of Neurology, University Duisburg-Essen, Germany.

Abstract
BACKGROUND: Hypnic headache (HH) is a RARE PRIMARY HEADACHE DISORDER THAT IS CHARACTERISED BY STRICTLY SLEEP-RELATED HEADACHE ATTACKS.

PURPOSE: Because of the low prevalence of this headache disorder, disease information is mainly based on case reports and small case series. This review summarises current knowledge on HH in regard to clinical presentation, pathophysiology, symptomatic causes and therapeutic options.

METHOD: We review all reported HH cases since its first description in 1988 by Raskin. Broadened diagnostic criteria were applied for patient selection that slightly deviate from the current ICHD-II criteria. Patients were allowed to describe the headache character to be other than dull. Additionally, accompanying mild trigemino-autonomic symptoms were permitted.

CONCLUSIONS: Mainly elderly patients are affected, but younger patients and even children might also suffer from HH. Headache attacks usually last between 15 and 180 minutes, but some patients report headache attacks up to 10 hours. Almost all patients REPORT MOTOR ACTIVITY DURING HEADACHE attacks. Cerebral MRI and 24-hour blood pressure monitoring should be performed in the diagnostic work-up of HH. Other primary headache disorders such as migraine and CLUSTER HEADACHE MAY ALSO PRESENT WITH SLEEP-RELATED HEADACHE ATTACKS AND SHOULD BE CONSIDERED FIRST. Caffeine taken as a cup of STRONG COFFEE SEEMS TO BE THE BEST ACUTE AND PROPHYLACTIC TREATMENT OPTION.

KEYWORDS: Hypnic headache, NREM, REM, hypothalamus, sleep

PMID:23832130[PubMed]

Like so many rare conditions it's not likely to get much attention in the competition for research $.

But, as with all the odd ball problems mentioned in the message, "Cluster-LIKE" headaches, it's a way of saying: don't be too fast & sure in making/treating a Dx of Cluster. Quite possible to treat the wrong condtion and so not find relief.