This study explores the prevalence of attributed causes of disturbed sleep and the association between stress-disturbed sleep and age, sex, and sleep duration on weekdays as well as weekends in a representative sample. A nationally representative sample (n = 1,128, response rate 72.8%), stratified for sex and age, completed a computer-assisted phone survey that included questions about sleep disturbances and attributed causes. Stress was the main attributed cause of sleep disturbance (35.1%), most frequently attributed by younger women (χ2 = 26.5, p < 0.001). Prevalence of stress-disturbed sleep was higher with lower age (B = −0.05, odds ratio (OR) = 0.94, CI = 0.91, 0.98). There was a trend, however, toward a significant interaction between age and sex, with women in the older age-groups more frequently reporting stress-disturbed sleep than older men (B = −0.02, OR = 1.022, CI = 1.003, 1.042). Weekday sleep duration decreased with increased stress-disturbed sleep, with an inverse relationship on weekends except for those reporting stress-disturbed sleep more than 5 days per week (F = 10.5, p < 0.001), who also had the shortest weekend sleep duration. Sleep disturbances were commonly attributed to stress, and more strongly so in women younger than 46 years. Stress-disturbed sleep during weekdays seems to be potentially compensated for with extended sleep on weekends, except for those with continuous stress-disturbed sleep.