Liability to anxiety and severe life events as predictors of new-onset sleep disturbances

Abstract

Study objectives: This study examined the effects of liability to anxiety and stressful life events on the onset of sleep disturbances.

Design: A 5-year longitudinal observational cohort study.

Participants: A population sample of 16,627 men and women with undisturbed sleep and 2572 with disturbed sleep at baseline.

Interventions: N/A.

Measurements and results: Liability to anxiety, as indicated by a general feeling of stressfulness (the Reeder stress inventory) and symptoms of sympathetic nervous system (SNS) hyperactivity, was assessed at baseline. The occurrence of post-baseline life events and sleep disturbances was measured at follow-up five years later. Both liability to anxiety and exposure to negative life events were strongly associated with sleep disturbances. Among the men liable to anxiety, the odds of sleep disturbances were 3.11 (95% CI 1.90-5.10) times higher for those who had experienced a severe life event within 6 months than for the others. For the men not liable to anxiety, the corresponding odds ratio was only 1.13 (95% CI 0.40-3.18). For the men and women liable to anxiety, the odds ratio for sleep disturbance 0-6 months after divorce was 2.05 (95% CI 1.38-3.05), with the corresponding odds ratio being 1.47 (95% CI 0.84-2.58) for the men and women not liable to anxiety. The effects of total or specific life events on sleep after 6 months were not dependent on liability to anxiety.

Conclusion: This study provides prospective evidence that individuals liable to anxiety may be at particularly high risk of post-event sleep disturbances at least during the first months after the event.

Figure 1

Effect of general feeling of stressfulness in daily life and symptoms of sympathetic nervous system (SNS) hyperactivity on the association between the severity of life events and the onset of disturbances Percentages of participants with sleep disturbances (95% confidence intervals) derived from a logistic regression analysis adjusted for age group and education. A participant was considered to be positive for sleep disturbance if he or she assessed the overall quality of sleep as being rather poor or poor. The baseline general feeling of stressfulness was assessed by the Reeder stress inventory (median split) and symptoms of SNS hyperactivity by the average experience of palpitation and sweating without exercise, irregular heartbeat, flushing, chest pain upon emotion, tremor of hands or voice, or muscle twitching (median split). Life events and their timing were measured at follow-up. Weights were determined as means of squared severity ratings for each event.

Figure 2

Effect of general feeling of stressfulness in daily life and symptoms of sympathetic nervous system (SNS) hyperactivity on the association between life events and the onset of sleep disturbances Percentages of participants with sleep disturbances (95% confidence intervals) derived from a logistic regression analysis adjusted for age group and education. A participant was considered to be positive for sleep disturbance if he or she assessed the overall quality of sleep as being rather poor or poor. The baseline general feeling of stressfulness was assessed by the Reeder stress inventory (median split) and symptoms of SNS hyperactivity by the average experience of palpitation and sweating without exercise, irregular heartbeat, flushing, chest pain upon emotion, tremor of hands or voice, or muscle twitching. Life events and their timing were measured at follow-up. Only events that occurred after the baseline measurements were considered.