Diurnally, CH exhibits a relationship with night-time and annually with daylight hours. Patients' sleep quality is reduced compared with controls. Results suggest a complex relationship as sleep quality improves between clusters, but remains pathological.

Despite a similar clinical phenotype, diurnal attack cycle is advanced by 1 hour in men with CH compared to women. Rhythmicity is a defining characteristic of CH and these findings suggest differences in the hypothalamus' influence on attack occurrence between the sexes. In addition, women were more often misdiagnosed and diagnosis in the primary or secondary sector more often failed. Furthermore, women had chronic CH more frequently than men. A long diagnostic delay and frequent misdiagnosis emphasize the need for increased awareness of CH in both sexes.

To date, this is the largest study of sleep in CH. It is demonstrated that REM sleep is affected which is in line with our current understanding of CH and hypothalamic involvement in the regulation of this sleep stage. Further, fewer arousals were found in CH patients but no association between apnea events or specific sleep stages. The findings support a central role of the hypothalamus and arousal systems in CH.

Aim To compare the prevalence of unhealthy lifestyle factors and comorbid disorders in cluster headache patients with headache-free controls, in order to discuss pathophysiology and possible consequences. Methods Cluster headache patients from the Danish cluster headache survey aged 18-65 years, diagnosed according to ICHD-II, were compared to sex- and age-matched headache-free controls. Participants completed questionnaires and structured interviews. Results A total of 400 cluster headache patients and 200 controls participated. Patients had a more unhealthy lifestyle compared with controls in the form of current and current/former smoking (48.3% vs. 9.0%, p < 0.001 and 74.5% vs. 30.0%, p < 0.001, respectively), higher average alcohol intake per week (98.2 grams vs. 77.9 grams, p = 0.033) and BMI (26.1 vs. 24.2 kg/m, p < 0.001), whereas coffee and energy drink consumption was equally distributed. Further, lifestyle-related, psychiatric and pain-related diseases were much more prevalent in patients compared with controls, except for diabetes. Sub-group analyses revealed that current/former smokers had a worse clinical presentation than never smokers. Conclusion Unhealthy lifestyle factors and lifestyle-related diseases were more prevalent in cluster headache patients compared to controls. As lifestyle-related diseases might have serious consequences in the management of cluster headache, it is key to inform patients at an early time point about the possible risks of their lifestyle choices.

Background and purpose Cluster headache (CH) is characterized by severe, unilateral attacks of pain and a high nocturnal attack burden. It remains unknown whether perturbations of sleep are solely present during the CH bout. Therefore, we aimed to investigate differences in sleep between the bout and remission period in patients with episodic CH and, secondly, to compare patients in the two phases with controls. Methods Patients with episodic CH (aged 18–65 years), diagnosed according to the International Classification of Headache Disorders 2nd edition, were admitted for polysomnography at the Danish Center for Sleep Medicine in bout and in remission. The macrostructure of sleep, including arousals, breathing parameters, limb movements and periodic limb movements, was compared with 25 age‐, sex‐ and body mass index‐matched healthy controls. Results There were no differences in any of the sleep parameters for patients in bout (n = 32) compared with patients in remission (n = 23). Attacks were unrelated to sleep stages, presence of apnea episodes, periodic limb movements, limb movements and arousals. In bout, patients had longer sleep latency (18.8 vs. 11.7 min, P < 0.05) and rapid eye movement sleep latency (1.7 vs. 1.2 h, P < 0.05) than controls and sleep efficiency was lower (82.5% vs. 86.5%, P < 0.05). Patients in remission only had a longer sleep latency compared with controls (17.5 vs. 11.7 min, P < 0.01). Conclusions The results support the presence of a continuing or slowly recovering disturbance of sleep outside the bout rather than a disturbance occurring secondary to attacks. Further, we confirm that there is no relation between CH attacks and specific sleep stages or between CH and breathing parameters.

Introduction In contrast to the premonitory phase of migraine, little is known about the pre-attack (prodromal) phase of a cluster headache. We aimed to describe the nature, prevalence, and duration of pre-attack symptoms in cluster headache. Methods Eighty patients with episodic cluster headache or chronic cluster headache, according to ICHD-3 beta criteria, were invited to participate. In this observational study, patients underwent a semi-structured interview where they were asked about the presence of 31 symptoms/signs in relation to a typical cluster headache attack. Symptoms included previously reported cluster headache pre-attack symptoms, premonitory migraine symptoms and accompanying symptoms of migraine and cluster headache. Results Pre-attack symptoms were reported by 83.3% of patients, with an average of 4.25 (SD 3.9) per patient. Local and painful symptoms, occurring with a median of 10 minutes before attack, were reported by 70%. Local and painless symptoms and signs, occurring with a median of 10 minutes before attack, were reported by 43.8% and general symptoms, occurring with a median of 20 minutes before attack, were reported by 62.5% of patients. Apart from a dull/aching sensation in the attack area being significantly ( p < 0.05) more frequent among men and episodic patients, compared with women and chronic patients respectively, no other differences in the prevalence of pre-attack symptoms were identified between groups. Conclusion Pre-attack symptoms are frequent in cluster headache. Since the origin of cluster headache attacks is still unresolved, studies of pre-attack symptoms could contribute to the understanding of cluster headache pathophysiology. Furthermore, identification and recognition of pre-attack symptoms could potentially allow earlier abortive treatment.

Purpose The purpose of this article is to investigate possible differences in effect between three types of masks in the acute treatment of cluster headache (CH). Patients and methods Fifty-seven CH patients according to ICHD-II-criteria participated in a single-blinded, semi-randomized, placebo-controlled, crossover inpatient study, and 102 CH attacks were treated with 100% oxygen delivered by demand valve oxygen (DVO), Optimask or simple mask (15 liters/min) or placebo delivered by DVO for 15 minutes. Primary endpoint: Two-point decrease of pain on a five-point rating scale within 15 minutes. Results Only 10 CH patients had multiple attacks and reached the point of placebo. There were no significant differences between masks in the primary endpoints ( p = 0.412). After 15 minutes 48% had a two-point decrease using the DVO compared to 45% with placebo ( p = 0.867). After 30 minutes 68% were pain free or had pain relief using DVO and 45% by placebo ( p = 0.061). The DVO was preferred by 62% compared to 5% and 33% for simple mask ( p < 0.0001) and Optimask ( p = 0.061). In the first attack the DVO was significantly better at achieving pain relief at 15 minutes ( p = 0.018). Treatment with DVO or Optimask reduced the need for rescue medication compared to the simple mask (23%, 19%, 50%, respectively). No treatment-related adverse events were observed. Conclusion The primary endpoint with pain relief at 15 minutes was non-significant; however, a post hoc analysis of the first attack significantly favored DVO. Further, therapy by Optimask and DVO resulted in a decreased need for rescue medication. We recommend that CH patients be offered DVO or Optimask before oxygen therapy is abandoned.

Aim To investigate the influence of clinical and demographic features on diagnostic delay in cluster headache patients, in order to discuss diagnostic pitfalls and raise disease awareness. Methods A large, well-characterized cohort of 400 validated cluster headache patients from the Danish Cluster Headache Survey, diagnosed according to ICHD-II, were investigated. ANOVA was applied to investigate differences in diagnostic delay between groups. Selected independent variables were assessed in relation to diagnostic delay using a gamma regression model. Results Diagnostic delay was significantly reduced for each decade of cluster headache onset from 1950–2010 ( p < 0.001). Onset after 1990 was associated with shorter diagnostic delay (OR = 0.28, p < 0.001), whereas attack duration > 180 minutes (OR = 1.62, p < 0.034), migraine-like features (OR = 1.30, p < 0.043) and nocturnal attacks (OR = 1.39, p < 0.021) were associated with prolonged diagnostic delay. Further, diagnostic delay decreased with age of onset (age < 20: 13.8 years, age 20–40: 5.4 years and age > 40: 2.1 years, p < 0.001). Conclusion Diagnostic delay was reduced for every decade investigated, whereas some atypical cluster headache features were associated with prolonged diagnostic delay. Better medical education and more disease awareness are needed to prevent misdiagnosis and prolonged diagnostic delay.