A significant association exists between sleep patterns and headaches among migraine sufferers, US study results suggest.

Writing in Headache: The Journal of Head and Face Pain, Drs Leslie Kelman, from the Headache Centre of Atlanta in Georgia, and Jeanetta Rains, from Dartmouth Medical Center in Lebanon, New Hampshire, explain: "The relationship between headache and sleep has been documented at least anecdotally in medical literature for well over a century and clinical texts allude to the importance of sleep as a headache precipitant."

However, they add that the nature of the relationship between sleep and headaches remains poorly understood.

To investigate further, the researchers studied 1283 migraine sufferers with an average age of 37 years, 84% of whom were female. All the participants underwent physical examinations and interviews to assess sleep and headache patterns. They were then divided into groups based on short, normal and long average sleeping patterns that were compared on the basis of headache characteristics.

The researchers found that sleep complaints were common among the participants, with over half experiencing difficulty initiating and maintaining sleep, and 38% sleeping for only around 6 hours a night (short). Many patients reported chronically shortened sleep patterns similar to those of people with insomnia.

Migraines were triggered by sleep disturbances in 50% of patients, while headaches that awakened them from sleep were reported by 71% of participants.

Patients with chronic migraine tended to have shorter nightly sleep patterns than those with episodic migraine, and were more likely to have trouble falling asleep and staying asleep. Short sleepers exhibited significantly more frequent and more severe headaches than individuals who slept longer and were more likely to have morning headaches on awakening.

Interestingly, sleep was also commonly used for symptom relief, with 85% of participants saying they chose to sleep or rest because of a headache, while 75% were forced to sleep or rest because of a headache.

Drs Kelman and Rains conclude: "These data support earlier research and anecdotal observations of a substantial sleep/migraine relationship, and implicate sleep disturbance in specific headache patterns and severity.

They add that further studies are needed to determine whether normalising sleep times in the "short sleepers" would reduce the number of headaches suffered by this group.