Examining the Relationship Between Worry and Sleep: A Daily Process Approach

There is growing evidence suggesting that worry and sleep are intimately linked. However, the relationship between these two phenomena over the course of a day remains largely unstudied. It is possible that (a) worry predicts sleep disturbance that night, (b) sleep disturbance predicts worry the following day, or (c) there is a bidirectional relationship between worry and sleep disturbance. The present study examined the daily relationship between worry (both during the day and immediately prior to sleep onset) and sleep in 50 high trait worriers who were randomly assigned to one of two interventions aimed at reducing worry as part of a larger study. A daily process approach was utilized wherein participants completed daily reports of sleep and worry during a 7-day baseline period followed by a 14-day intervention period. Results of repeated measures multilevel modeling analyses indicated that worry experienced on a particular day predicted increased sleep disturbance that night during both the baseline and intervention weeks. However, there was no evidence of a bidirectional relationship as sleep characteristics did not predict worry the following day. Additionally, the type of intervention that participants engaged in did not affect the daily relationship between worry and sleep. Results of the present study are consistent with the cognitive model of insomnia (Harvey, 2002) and highlight the importance of addressing and treating worry among individuals with high trait worry and sleep disturbance.