title: Diurnal variation of tension-type headache intensity and exacerbation: An investigation using computerized ecological momentary assessment.
abstract: BACKGROUND
  Tension-type headache is a common psychosomatic disease. However, diurnal variation of headache is yet to be clarified, perhaps due to the lack of an appropriate method to investigate it. Like other painful diseases, it would be helpful to know if there is diurnal variation in tension-type headaches, both for managing headaches and understanding their pathophysiology. The aim of this study was to determine if there is diurnal variation in the intensity and exacerbation of tension-type headache.
  
  
  METHODS
  Patients (N = 31) with tension-type headache recorded for one week their momentary headache intensity several times a day and their acute headache exacerbations using a watch-type computer as an electronic diary (computerized ecological momentary assessment). Multilevel modeling was used to test the effects of time of day on momentary headache intensity and on the occurrence of acute exacerbations.
  
  
  RESULTS
  A significant diurnal variation in momentary headache intensity was shown (P = 0.0005), with the weakest headaches in the morning and a peak in the late afternoon. A between-individual difference in the diurnal pattern was suggested. On-demand medication use was associated with a different diurnal pattern (P = 0.025), suggesting that headache intensity decreases earlier in the evening in subjects who used on-demand medication, while headache subtype, prophylactic medication use, and sex were not associated with the difference. The occurrence of acute headache exacerbation also showed a significant diurnal variation, with a peak after noon (P = 0.0015).
  
  
  CONCLUSIONS
  Tension-type headache was shown to have a significant diurnal variation. The relation to pathophysiology and psychosocial aspects needs to be further explored.
authors.affiliation: Department of Psychosomatic Research, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8553, Japan. kikuchih-tky@umin.ac.jp.
authors.forename: Hiroe
authors.initials: H
authors.lastname: Kikuchi
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yoshiuchi
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Gen
authors.initials: G
authors.lastname: Komaki
authors.forename: Akira
authors.initials: A
authors.lastname: Akabayashi