Insomnia Is Common and Includes Symptoms Such as Difficulty Falling Asleep or Staying

INSOMNIA IS COMMON AND INCLUDES SYMPTOMS SUCH AS DIFFICULTY FALLING ASLEEP OR STAYING ASLEEP, EARLY MORNING WAKENING, AND SLEEP dissatisfaction, as well as daytime consequences such as tiredness.1 Studies of general-population samples have found the prevalence of insomnia to range between 10% and 48%.2,3 Much of this variation in prevalence may be explained by the use of different definitions of insomnia in these studies.1 Insomnia can have important consequences for sufferers and may impact on health, work, and quality of life. Such associations include the development of depression,2 increased use of health care services4,5 and a higher risk of motor vehicle accidents.6 In addition, studies looking at the relationship between insomnia and work have found associations with absenteeism, decreased concentration, impaired work performance and work related accidents.5,7 Cross-sectional studies of insomnia have consistently found female sex,1,2,8 mental health problems,2,4,9,10 and physical health problems11-14 to be associated with an increased prevalence. A link between increasing age and insomnia has been reported,1,4 although this finding is not consistent.8,15,16 A small number of epidemiologic studies have looked at the relationship between pain and insomnia.15,17 Although there are numerous cross-sectional studies investigating prevalence of insomnia in the USA11,18-20 and Europe,3,4,16,2125 including the UK,9 less is known about the onset and natural history of insomnia. Many of these studies have highlighted factors associated with prevalent insomnia, and it is not clear what is cause and effect or whether the factors are linked with the onset or persistence of the problem. Longitudinal studies can help to unravel these associations. The aims of this study were to investigate the incidence and persistence of insomnia and factors associated with these, and insomnia as a risk factor for anxiety, depression, and pain, in a longitudinal study of an adult, UK, general-population sample.