Hypnic Headache – Alarm Clock Precision

What is Hypnic Headache?

Hypnic Headache is a rare primary headache that only develops during sleep and always wakes the sufferer. It’s been dubbed the ‘alarm clock’ headache due to this phenomenon. It’s twice as likely to occur in women as men and usually strikes between 1 am – 3 am each time.

The headache itself generally lasts between 15 minutes and 2 hours after waking. It mostly occurs from the age of 50 years, but can occur in younger people as well. The pain can range from mild to severe and is usually on both sides of the head. Sometimes people also suffer from accompanying migraine symptoms including nausea.

To get a proper diagnosis of Hypnic Headache your doctor should take a full history of your sleep patterns and night time habits (including any snoring). This helps to count out any secondary causes of headaches which start at night. Other primary headaches (such as migraine, cluster headaches and chronic paroxysmal hemicrania) can also wake you at night so these need to be excluded before you can be sure that you have Hypnic headache.

Now for the Science Part

Here’s the Diagnostic Classification according to the International Headache Society…

4.9 Hypnic headache

Previously used terms: Hypnic headache syndrome; ‘alarm clock’ headache.

Description:

Frequently recurring headache attacks developing only during sleep, causing wakening and lasting for up to four hours, without characteristic associated symptoms and not attributed to other pathology.

Diagnostic criteria:

1. Recurrent headache attacks fulfilling criteria B–E
2. Developing only during sleep, and causing wakening
3. Occurring on _10 days/month for >3 months
4. Lasting from 15 minutes up to four hours after waking
5. No cranial autonomic symptoms or restlessness
6. Not better accounted for by another ICHD-3 diagnosis

Notes:

1. Distinction from one of the types or subtypes of Trigeminal autonomic cephalalgias, especially Cluster headache, is necessary for effective management.
2. Other possible causes of headache developing during and causing wakening from sleep should be ruled out, with particular attention given to sleep apnoea, nocturnal hypertension, hypoglycaemia and medication overuse; intracranial disorders must also be excluded. However, the presence of sleep apnoea syndrome does not necessarily exclude the diagnosis of Hypnic Headache

What triggers Hypnic Headache?

We don’t really know is the long and short of it. There’s evidence to suggest that it only occurs during REM sleep and that during this time “observations suggest that pain processing structures are activated during REM sleep….Some authors have described nightly headache attacks due to hypertension, which might also occur during REM sleep.” From https://pn.bmj.com/content/practneurol/5/3/144.full.pdf

How do you treat it?

The most common and successful treatment is Lithium Carbonate but believe it or not, a cup of coffee or can of Coke before bed can keep Hypnic Headache at bay, however this doesn’t work for everyone so other medications used include;

• Melatonin
• Flunarizine
• Indomethacin
• Topiramate
• Lithium carbonate – used with caution especially in the presence of kidney disease, thyroid disease, dehydration, or use of diuretics.

What’s the prognosis?

It’s very important to rule out other causes as sudden onset of a headache in the over 50s can be an indication of more serious problems, but if Hypnic headache is the diagnosis then that’s okay as even though it is painful, it’s a completely benign headache. Monitoring sleep patterns and types of sleep (deep, light, REM) may be beneficial.