Hypnic headache involves attacks of a dull headache that always awakens sufferers from sleep. Unlike cluster headache (CH) there are normally no associated autonomic symptoms. Although the pain is normally classified as mild to moderate, severe pain can exist amongst up to 20% of sufferers and the headache is bi-lateral (both sides) in up to two thirds of cases.
Hypnic headache also differs from CH in that it is more likely to occur amongst much older people and females. The headaches are brief - lasting between 5 minutes and 3 hours - and can occur up to three times per night. These can generally be effectively treated by bedtime dosages of lithium, indomethacin or caffeine.