Sleep and insomnia markers in the general population

Several epidemiological surveys performed in Western Europe reported a prevalence of insomnia symptoms between 20% and 40% of the general population. Women and elderly individuals were the most affected. Many events can occur during sleep and affect its quality. Daytime sleepiness, a consequence of lack of sleep and/or insomnia, is responsible for many road, work and domestic accidents. Therefore, insomnia may have important consequences both for individuals and society. This study performed in the non institutionalized French population reports the sleep habits of that population and the factors associated with insomnia. This epidemiological study was conducted with 5 622 subjects representative of the French general population. They were aged between 15 and 96 years. The participation rate was 80.8%. The results showed that men and women have different sleep habits. Generally speaking, women went to bed about 12 minutes earlier than men and woke up later than men (p < 0.001). Women also took more time to fall asleep than men but only when they were aged between 35 and 65 years. Furthermore, women had a longer sleep than men except between the ages of 55 and 74, where men slept significantly more than women. However, sleep efficiency was lower in women than in men who were overage 35. This was due to a greater frequency of nocturnal awakenings in women than in men. Sleep habits also changed with age: Bedtime became progressively earlier with advancing age and wake-up time was later when the subjects reached retirement age. Sleep latency progressively increased with age after 35. Similarly, disrupted sleep increased with age and was reported by more than half of subjects 75 years or older. We found also that evening or night workers showed irregularities in their sleep patterns: sleep latency was significantly longer - at least 12 minutes compared to daytime and shift workers (p < 0.001). They also had a shorter sleep duration of about 30 minutes compared to shift workers, and 40 minutes compared to daytime workers (p < 0.001). Shift workers and evening or night workers had a lower sleep efficiency compared to daytime workers. Finally, in regions with greater density population (> 100 000 inhabitants) sleep duration was shorter by approximately 10 minutes compared to localities with fewer than 5 000 residents (p < 0.01). Similarly, bedtime and wake up hours were more related in regions with more than 100 000 inhabitants compared to small localities (fewer than 5 000 residents). Insomnia complaints, defined as the presence of at least one insomnia symptom accompanied by sleep dissatisfaction or use of a sleep medication, were reported by 18.6% of the sample. The prevalence was higher in women (22.4%) than in men (14.5%) and increased with age. However, the proportion of subjects dissatisfied with their sleep remained comparable for all age groups; it was the number of subjects using a sleep medication that increased with age. This was 3.2% in subjects 44 years or younger, 13.3% in subjects between 45 and 64 years, 22% of those between 65 and 74 years and almost a third of individuals 75 years or older (32%; p < 0.001). However, insomnia symptoms remained present for most of these consumers: 80.4% of those between 15 and 44 years, 87.9% of those between 45 and 64 years, 81.4% of those between 65 and 74 years and 78.8% of subjects of 75 years or older. Compared to subjects in other epidemiological studies undertaken in England, Germany and Italy and using the same methodology, subjects in this study complained with their sleep more often. Insufficient sleep was found more often in the active population, which is subject to schedule constraints. Shift workers as well as evening or night workers were the most likely to have a sleep debt.