title: Night-time thoughts in high and low worriers: reaction to caffeine-induced sleeplessness.
abstract: There is ample evidence for the existence of an association between sleeplessness and worry. Not much is known, however, concerning the nature of this relationship. Therefore, a study was conducted investigating the causal relationship between sleeplessness and nocturnal worry. A 2 x 2 (Worry x Induced sleeplessness) analysis of covariance design was used. The first factor consisted of a subject variable defined by scoring either high or low on a trait measure of worry (the Penn State Worry Questionnaire) and the second factor consisted of 300 mg caffeine or placebo. A total of 96 female undergraduate students participated. The dependent variables comprised measures of nocturnal worry (the Night-Time Thoughts Questionnaire) and subjective and objective sleep parameters. Overall, caffeine caused an increase in nocturnal worry and sleeplessness. A significant interaction effect occurred between Worry and Induced sleeplessness on one of the objective sleep parameters, but no other interaction effects were significant. The results suggest that worry may occur as an epiphenomenon of sleeplessness.
authors.affiliation: Department of Clinical Psychology, University of Bergen, Christies Gate 12, 5015 Bergen, Norway. siri.omvik@psykp.uib.no
authors.forename: Siri
authors.initials: S
authors.lastname: Omvik
authors.forename: Ståle
authors.initials: S
authors.lastname: Pallesen
authors.forename: Bjørn
authors.initials: B
authors.lastname: Bjorvatn
authors.forename: Julian
authors.initials: J
authors.lastname: Thayer
authors.forename: Inger Hilde
authors.initials: IH
authors.lastname: Nordhus
mesh_terms: D000293:Adolescent; D000328:Adult; D001007:Anxiety / Q000209:etiology*; D002110:Caffeine; D005260:Female; D006801:Humans; D011594:Psychometrics; D007319:Sleep Initiation and Maintenance Disorders / Q000139:chemically induced / Q000523:psychology*
chemical_list: D002110:Caffeine