Sleep-related symptoms are associated with painful conditions, partly because pain may interfere with sleep and vice versa. This dual cause and effect relationship has been known for many years through clinical experience with headache patients. The scientific literature addressing comorbidity of headache and sleep disturbances is growing.
Many epidemiological studies have evaluated the association with sleep apnea to nonspecific headache diagnoses (e.g. headache, morning headache, chronic daily headache), whereas relatively few epidemiological studies have focused on the specific diagnosis of tension-type headache (TTH). TTH is associated with sleep disorders, and subjects with TTH often report sleep complaints related to insomnia.
The impact of sleep complaints in migraineurs has been studied more extensively. Migraine is associated with several sleep problems, and this observation is supported by polysomnographic findings. Also, excess of sleep, insufficient sleep duration, and poor sleep quality are common triggering factors for migraine attacks.
According to a study from Sweden, severe sleep disturbance were five times more likely among migraineurs, and three times more likely among subjects with TTH. Other studies using different types of questionnaires have also reported a higher prevalence of sleep disturbances among migraineur and subjects with TTH, respectively. Studies have reported a higher prevalence of daytime sleepiness among migraineurs and insomnia among subjects with TTH.
A study found that the association between headache and severe sleep disturbance increased markedly in relation to the headache frequency. In accordance with other studies, the prevalence of sleep disturbances increased with higher frequency of headache/days per month and that subjects with chronic headache had more sleep disturbances compared with subjects with episodic headaches.