The purpose of this study is to assess both the sleep and circadian (24-hourly biological rhythms) physiology of people with cluster headache. For sufferers with the episodic form of the disorder this will involve observation at two separate time points, once when experiencing attacks (in-bout) and once when attack free (out-of-bout).

The study will include measurement of basic rest-activity patterns, sleep timing and timing of individual attacks, as well as a more detailed study recording sleep and circadian rhythms under clinical conditions over consecutive nights.

Studying the differences in these processes in single individuals when they are both experiencing and free from attacks might provide insight into the brain mechanisms involved in triggering the bouts of attacks and individual attacks themselves. An improved understanding of this area may help design improved treatment options in future.

Inclusion Criteria:

• Diagnosis of cluster headache or closely related primary headache disorder

Exclusion Criteria:

• Abnormality on screening investigations that increase risk of participation
• Alcohol consumption exceeding 21 units per week

Cluster headache sufferers (both of the episodic and chronic cluster headache) Related headache disorders