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 way that these two phenomena influence each other over the course of a day is largely unknown. Specifically, it is possible that (1) worry contributes to sleep disturbance, (2) sleep disturbance contributes to worry, or (3) there is a bidirectional relationship between worry and sleep. The present study examined the daily relationship between worry and sleep in 53 high trait worriers who were randomly assigned to one of two interventions aimed at reducing worry. A daily process approach was utilized wherein participants completed daily reports of sleep and worry during a 7-day baseline period, as well as daily reports of sleep, worry, and emotion during 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, neither intervention nor daily emotional functioning affected the daily relationship between worry and sleep. Results of the present study are consistent with the cognitive model of insomnia (Harvey, 2002) and suggest that worry experienced throughout the day and prior to sleep onset has negative effects on sleep. Contrary to our hypotheses, there was no evidence suggesting that sleep disturbance affects worry symptoms. Results highlight the importance of addressing and treating worry among individuals with high trait worry and sleep disturbance.