1 Department of Psychology, Concordia University, 7141 Sherbrooke St W, Montréal H4B?1R6, Canada; Center for Clinical Research in Health, Concordia University, 7141 Sherbrooke St W, Montréal H4B?1R6, Canada; PERFORM Center, Concordia University, 7141 Sherbrooke St W, Montréal H4B?1R6, Canada. Electronic address: jp.gouin@concordia.ca.
2 Department of Psychology, Concordia University, 7141 Sherbrooke St W, Montréal H4B?1R6, Canada.
3 PERFORM Center, Concordia University, 7141 Sherbrooke St W, Montréal H4B?1R6, Canada; Center for Studies in Behavioral Neurobiology and Department of Exercise Science, Concordia University, 7141 Sherbrooke St W, Montréal H4B?1R6, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, 4545 chemin Queen-Mary, Montréal H3W?1W5, Canada.
4 Department of Psychology, Concordia University, 7141 Sherbrooke St W, Montréal H4B?1R6, Canada; Center for Clinical Research in Health, Concordia University, 7141 Sherbrooke St W, Montréal H4B?1R6, Canada; PERFORM Center, Concordia University, 7141 Sherbrooke St W, Montréal H4B?1R6, Canada; Center for Studies in Behavioral Neurobiology and Department of Exercise Science, Concordia University, 7141 Sherbrooke St W, Montréal H4B?1R6, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, 4545 chemin Queen-Mary, Montréal H3W?1W5, Canada.

Objective: The aim of this study was to evaluate whether high-frequency heart rate variability (HF-HRV) during waking restfulness and during worry predicts increases in sleep disturbances in response to a stressful life event.

Methods: A longitudinal study following up 22 individuals from well-defined periods of lower and higher stress was conducted. HF-HRV during waking restfulness and in response to a worry induction was measured during a low-stress period. Sleep disturbances were assessed using the Pittsburgh Sleep Quality Index (PSQI) and the Insomnia Severity Index (ISI) during low-stress and high-stress periods.

Results: During both the low- and high-stress periods, lower HF-HRV during worry was associated with greater PSQI scores. Importantly, lower HF-HRV during the worry induction prospectively predicted greater increases in the PSQI score from the low-stress to the high-stress periods.

Conclusion: HF-HRV during worry might represent an index of vulnerability to stress-induced sleep disturbances.