What is Hypnic Headache (Alarm Clock Headache)?
Headaches and chronic pain are some of the top reasons for health-related suffering and disability worldwide. There are many different types of headaches, categorized based on specific criteria. One such type is the hypnic headache.
Hypnic headaches are unusual, occurring only during sleep and typically at the same time each night. They have been previously referred to as ‘clockwise headaches’ or ‘alarm clock headaches’. According to the global headache classification standards, they are recognized as a primary type of headache.
These headaches are usually dull in sensation, happening 15 times or more in a month, and only during sleep. The symptoms typically start to appear after the age of 50 without any accompanying symptoms. The patient is often woken up by the pain which generally lasts for more than 15 minutes after awakening.
Hypnic headaches are a long-term condition, persisting for years without any relief from the headaches.
People with migraines and high blood pressure are more susceptible to developing this type of headache. Nearly all patients suffering from hypnic headaches had some sort of movement activity, like getting out of bed or eating, drinking, showering, or reading when awakened by the headache. However, they did not normally exhibit the restlessness seen with other types of headaches like cluster headaches and trigeminal autonomic cephalalgias.
What Causes Hypnic Headache (Alarm Clock Headache)?
The exact cause of Hypnic Headaches (HH) is not completely known. However, these headaches might be linked to problems in certain areas of the brain. These areas are responsible for managing pain, producing a hormone called melatonin, or controlling the part of sleep known as REM (Rapid Eye Movement) sleep.
Risk Factors and Frequency for Hypnic Headache (Alarm Clock Headache)
A hypnic headache is a relatively rare condition, accounting for about 0.07% of all patients seeking medical help for headaches.
- In older adults, this type of headache is slightly more common, with about 1.4% experiencing it according to a study in Italy.
- Recent studies indicate that hypnic headaches might be more common than previously thought. A French study approximates the occurrence rate between 0.3% to 0.6%.
Signs and Symptoms of Hypnic Headache (Alarm Clock Headache)
People who experience hypnic headaches typically describe them as frequent recurring headaches that only occur during sleep. These headaches wake them up and can last for as long as 4 hours. Normally, these headaches do not come with other symptoms and are not linked to other health issues.
According to the ICHD-3, the formal criteria for hypnic headaches include:
- They develop only during sleep and cause the person to awaken
- They occur at least 10 days per month for at least 3 months
- Once the person awakens, they last at least 15 minutes but no longer than 4 hours
- They do not come with any cranial autonomic symptoms or restlessness
Also, these headaches should not be explained by another ICHD-3 diagnosis.
Other typical features of hypnic headaches are:
- Timing: These headaches usually occur exclusively during sleep with a daily rhythm
- Age: While this condition is seen more in older people (more than 50 years old), it can occur in younger people as well
- Gender: Both men and women seem to be affected equally
- Duration: Hypnic headaches are usually short and last between 30 to 60 minutes, but they can extend up to 3 hours
- Intensity: They are mostly moderate to severe in intensity, but a small group of people report having mild headaches
- Character: They are often described as dull, but can also be throbbing or pulsating
- Location: Hypnic headaches are usually felt on both sides of the head and are generally spread out
These types of headaches are rarely accompanied by symptoms typical of migraines (like nausea, vomiting, or sensitivity to light and sound) or autonomic symptoms (like tearing or redness in the eyes).
Testing for Hypnic Headache (Alarm Clock Headache)
If you often have headaches at night, your doctor will need to check if certain conditions may be causing your pain. These conditions can include brain tumors, giant cell arteritis (an inflammation of the blood vessels in the head), obstructive sleep apnea (a condition where breathing stops and starts during sleep), and other sleep-related disorders.
Your doctor may ask for a brain MRI scan, with or without contrast dye, to check for any structural problems in your brain, such as tumors. Additionally, you may require an overnight sleep study known as polysomnography. This test can help to confirm or rule out conditions like obstructive sleep apnea and other sleep disorders.
Once all physical causes for the headaches have been ruled out, your diagnosis will largely be based on specific diagnostic criteria set by the International Classification of Headache Disorders (ICHD-3). An MRI scan of the brain might also show a decrease in the size of grey matter (an important part of the central nervous system) in the hypothalamus, an area of your brain.
Treatment Options for Hypnic Headache (Alarm Clock Headache)
Treating headaches can be difficult and requires a thorough check-up. While there isn’t much detailed data on how to manage a specific type of headache, known as hypnic headaches, certain medications have demonstrated benefits.
Lithium, a commonly used treatment according to research reports, has seen success in treating hypnic headaches. Depending on the individual case, the effective dose can range from 150 to 600 mg/day. The levels in the blood should ideally be between 0.5 to 1.0 mmol/L.
Indomethacin, another medication, has also shown promising results, especially in patients with one-sided hypnic headaches or those with certain related physical symptoms. The usual dose is 25 to 150 mg taken before bed. However, doctors need to be aware of possible side effects, particularly in older people.
Caffeine, in doses of 40 to 60 mg, has turned out to be a good treatment option for hypnic headaches. Interestingly, it does not impact the sleep of elderly people, who usually tolerate it well. Hence, it’s commonly the first choice of treatment for these headaches.
Other medications like antidepressants, beta-blockers, verapamil, NSAIDs, prednisolone, other anticonvulsants, acetazolamide, melatonin, benzodiazepines, pizotifen, and topiramate, have been tried. However, their effectiveness is not very clear, and evidence is conflicting. Some case reports suggest that onabotulinum toxin and occipital nerve stimulation might be effective, but doctors need to be careful about the potential complications of such treatments.
What else can Hypnic Headache (Alarm Clock Headache) be?
If you’re experiencing a nighttime headache, there could be a variety of causes. While hypnic headache is one possibility, there are other types of headaches that also commonly occur during sleep. These may include migraines, cluster headaches (which typically cause severe pain behind one eye), cervicogenic headaches (caused by neck issues), or SUNCT (short-lasting headaches with eye watering and other symptoms). It’s crucial to determine the right diagnosis so that the correct treatment can be given.
What to expect with Hypnic Headache (Alarm Clock Headache)
Reports suggest that about 17% of patients naturally get better over time. However, a majority of patients still experience chronic symptoms. There’s some good news though, as another study shows that with treatment, 40% of patients managed to completely get rid of their headaches. Interestingly, another study revealed that more than half of the patients, precisely 53%, have episodes of relief after undergoing treatment.
Possible Complications When Diagnosed with Hypnic Headache (Alarm Clock Headache)
There are no reported long-term impacts on the nervous system due to this condition.
Preventing Hypnic Headache (Alarm Clock Headache)
The precise cause and nature of headaches are still not fully understood, making prevention currently impossible. However, preventive measures have shown promising results in lessening the occurrences of headache attacks.