Cluster Headaches and the Relationship to Sleep and Sleep Apnea

REM Sleep and Sleep Apnea Are Closely Linked to Cluster Headaches

Cluster headaches and sleep depend on similar structures
Cluster headaches and sleep depend on similar structures. SCIEPRO/Science Photo Library/Getty Images

Cluster headaches are an extremely painful condition that is closely linked to both oxygen levels and sleep. How do cluster headaches interact with sleep and sleep apnea? Learn about the symptoms, causes, and role of sleep in cluster headaches.

Reviewing the Basics of Headaches and Sleep

Sleep-related headaches occur exclusively during sleep or shortly after awakening and vary in severity and duration.

These headaches may affect one side (unilateral) or both sides (bilateral) of the head. In the case of cluster headaches, the pain is unilateral. There are also pains that need to be excluded that affect the head and may be due to other medical, neurological, psychiatric, or sleep disorders.

Many headaches can occur both during wakefulness and sleep, including migraine, cluster, and chronic paroxysmal hemicrania headaches. Some headaches occur exclusively in sleep (these are called hypnic headaches).

Sleep is a state initiated by and dependent on processes within the brain. It would make sense that another condition that also occurs in association with the head may have some overlapping anatomy or chemical basis. The structures of the brainstem and posterior hypothalamus are important to both sleep and headache. In addition, similar chemicals within the brain - including adenosine, melatonin, and orexin - are important to both phenomena.

What Causes Cluster Headaches?

Cluster headaches tend to have a strong family history and may be incited by clearly identified triggers. Close relatives (such as parents or siblings) have seven times the risk of cluster headaches. Identical twins virtually always share the condition if it is present.

Alcohol is a common trigger of cluster headaches. In general, low blood oxygen levels (hypoxia) also play a role. Sleep apnea, in which the upper airway collapses during sleep resulting in sleep fragmentation or decreased oxygen levels, may independently lead to morning headaches. This occurs due to retention of carbon dioxide overnight acting as a dilator of blood vessels in the brain and increasing pressure in the head. Moreover, the resulting hypoxia could trigger cluster headaches in susceptible individuals.

General changes in sleep patterns, including insomnia, may predispose to more cluster headache attacks.

The Symptoms of Cluster Headaches

Cluster headaches are easily differentiated from other headaches due to the unique constellation of symptoms. The headache pain is quite severe and unilateral, usually around the eye or temple. The pain starts very quickly and peaks within 10 to 15 minutes. The duration of the headache ranges from 15 minute to 3 hours, often lasting about 1 hour.

Cluster headaches are also associated with other findings, including:

  • Eye redness (conjunctival injection)
  • Tearing
  • Nasal congestion
  • Runny nose
  • Forehead or face sweating
  • Pinpoint pupil
  • Droopy eyelid
  • Eyelid swelling

The name is derived from the “clusters” of headaches that occur one to three times per day over a period of 1 to 2 months before dissipating. In general, people with cluster headache tend to experience one period of headaches per year. The average age of onset is 29 years old. The pain-free intervals may last months to a few years and the headaches tend to decrease with age.

The timing of these headaches is interesting, and often associated with sleep. Cluster headaches tend to occur at the same hour each day. It is estimated that 75% of cluster episodes occur between 9 PM and 10 AM.

Cluster Headaches and the Relationship to Sleep

It is estimated that of the 17 percent of people who go to a headache clinic complaining of nighttime or early morning headaches, about half had headaches that were due to an underlying sleep disorder such as sleep apnea. As noted, the oxygen level changes may provoke cluster headaches in susceptible individuals.

There is a strong association between cluster headaches and REM sleep. This makes sense as this state is characterized by decreased muscle tone, to prevent dream enactment, and this increases the risk of sleep apnea.

Due to the extreme pain, cluster headaches themselves can contribute to sleep disruption and insomnia. This may resolve as the headache cluster remits or is effectively treated.

If you experience symptoms that are suggestive of cluster headaches, be certain to speak with your doctor. It may be important to seek additional evaluation by a general neurologist, headache specialist, or sleep specialist. After a careful evaluation, the proper treatments can be selected to provide you the comfort and relief that you need to sleep and feel better.


American Academy of Sleep Medicine. International classification of sleep disorders, 3rd ed. Darien, IL: American Academy of Sleep Medicine, 2014

Bartleson JD, Black DF, Swanson JW. Cranial and Facial Pain. pp. 263-269. In Bradley

Brennan KC, Charles A. Sleep and headache. Semin Neurol 2009; 29:406-417.

International Headache Society Classification Subcommittee. 2004, International classification of headache disorders, 2nd ed., Cephalgia, vol. 24, suppl. 1, pp. 1-60.

Continue Reading