Definition and Overview
Hypnic headaches are rare primary headaches that occur only during sleep and wake the patient from sleep. It is characterized by the fact that it does not occur while awake but only occurs while asleep, and it is also called an ‘alarm clock headache’ as it recurs at the same time almost every day.
It commonly occurs after the age of 50 and is considered a cause of nighttime headaches in older people.
Epidemiology
Hypnic headaches are rare primary headaches that usually begin after the age of 50. The average age of onset is reported to be in the 60s, and compared to other primary headaches, it is characterized by new onset at an older age.
symptoms
headache pattern
- Occurrence point: Occurs only during sleep and wakes the patient
- Repetitive: Repeats at about the same time almost every day (often several hours after going to sleep)
- Pain location: Bilateral dull pain is common.
- Duration: 15 minutes to several hours after awakening
Unlike cluster headaches, the fact that autonomic symptoms or restlessness during attacks are not prominent is helpful for differentiation.
diagnosis
The diagnosis is a clinical diagnosis according to the International Classification of Headache Disorders, Third Edition (ICHD-3) criteria. Diagnostic criteria include headaches that occur only during sleep and wake you up, occur more than 10 days per month, last more than 15 minutes after awakening, and cannot be explained by another headache disorder.
For headaches that wake you up at night, secondary causes such as increased intracranial pressure due to a brain tumor, nocturnal hypertension, obstructive sleep apnea, and cluster headaches must first be ruled out. Since this is a new-onset nocturnal headache in an elderly person, brain imaging is recommended.
treatment
caffeine before bed
Consuming caffeine before bed is often effective in preventing it. Although caffeine generally interferes with sleep, it has been reported to reduce nocturnal headaches in patients with hypnic headaches without significantly interfering with sleep, so it is attempted as primary prevention.
Lithium and other drugs
Lithium is used as preventive treatment, and indomethacin and melatonin have also been reported. Lithium requires monitoring of blood levels and side effects, so it should be used under professional supervision.
Clinical implications
If an elderly person is observed to wake up with a headache at the same time almost every day, a hypnic headache is considered. However, because the risk of secondary headaches is high in the same age group, it is important to rule out secondary causes through imaging tests, nighttime blood pressure, and sleep apnea evaluation prior to diagnosis.