Anxiety mediates the effect of smoking on insomnia in people with asthma: evidence from the HUNT3 study

Abstract

Objective

The aim of this study was to investigate factors related to insomnia in a cohort of people with asthma.

Design

This secondary analysis utilized cross-sectional data from the Norwegian Nord-Trøndelag Health Study, a population-based health survey (n=50,807).

Participants

We used self-reported data from 1,342 men and women with a physician-confirmed asthma diagnosis ranging in age from 19.5 to 91 years.

Measurements

Data on sleep, lifestyle variables (smoking and exercise), anxiety, and depression were included. An insomnia scale and asthma impact scale were constructed using factor analysis. Hierarchical series of multiple regression models were used to investigate direct and mediational relationships between the study variables and insomnia.

Results

The hierarchical models revealed significant independent contributions of female sex, higher age, not exercising, asthma impact, anxiety, and depression on insomnia (R²=25.2%). Further, these models suggested that the impact of smoking on insomnia was mediated by anxiety, and that the beneficial impact of exercise was mitigated by depression symptoms.

Conclusion

Smokers with asthma have more insomnia, and this relationship may be mediated by anxiety. Further, people with asthma who experience depression symptoms are less likely to benefit from physical exercise as a method to enhance sleep quality. Our findings would suggest that helping smokers to manage their anxiety and depression through behavioral methods may reduce their insomnia symptoms, and enable them to engage in other health-enhancing pursuits, such as physical exercise.

Keywords:

• insomnia
• asthma
• anxiety
• depression
• smoking
• mediation

Acknowledgments

The Nord-Trøndelag Health Study (the HUNT study) is a collaboration between the HUNT Research Centre (Faculty of Medicine, Norwegian University of Science and Technology), the Nord-Trøndelag County Council, the Central Norway Health Authority, and the Norwegian Institute of Public Health. The authors thank Carolina Campos, RN, MNSc for helpful discussions earlier in the course of this project. This study was performed at the Department of Nursing and Health Promotion, Oslo and Akershus University College, Oslo, Norway.

Author contributions

Both authors contributed to the conception and design, analysis, and interpretation of data. Further, RA drafted the article with substantial contributions from CES, and both authors revised it critically for important intellectual content, and approved the final version. The authors agree that they are accountable for all aspects of the work, confirming that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Disclosure

The authors report no other conflicts of interest in this work.