Background While short and long sleep duration and poor sleep quality have individually been linked to work disability and ill-health, their joint impact on functioning has received less attention. The aim was to examine the joint associations of sleep quantity and quality with physical, emotional, and social functioning, while considering the contribution of key potential confounders.

Methods Data from the nationally representative Household, Income and Labour Dynamics in Australia (HILDA) Study, collected in 2013, were used (n=14557). Poor sleep quality (yes/no) was examined in combination with normal (6–8 hours), short (<6) or long (>8) sleep. Short form SF-12 questionnaire was used to examine functioning. Covariates included sociodemographic factors, social connexions (meeting with friends), health behaviours, obesity, pain, and mental and physical illnesses. Logistic regression analysis was used (odd ratios, OR and their 95% confidence intervals, 95% CI).

Results After adjusting for sex and age, short, normal and long sleep duration in combination with poor quality were all associated with poorer physical, emotional and social functioning. The associations were relatively similar for physical and emotional functioning, and strongest for social functioning (OR 3.36, 95% CI 2.94–3.84 for normal sleep with poor sleep quality, OR 4.56, 95% CI 4.02–5.17 for short sleep with poor sleep quality and OR 7.83, CI 95% 6.09–10.09 for long sleep with poor sleep quality). Also people with good sleep quality but short or long sleep had poorer functioning, but the associations were weaker for all forms of functioning (ORs ranging 1.28–1.57 after adjusting for sex and age). Pain and comorbid illness attenuated all of the associations the most, while the contributions of the other covariates were relatively minor. However, the associations remained after full adjustments for people with poor sleep quality and short, normal or long sleep, and for people with good sleep quality but long sleep duration.

Conclusion The results highlight that in particular poor sleep quality is likely to have the most severe consequences for daytime functioning in the general population, and that there is little difference between short and normal sleepers in the presence of poor quality sleep.