The Epidemiology of Insomnia and Sleep Duration Across Mental and Physical Health: The SHoT Study

Abstract

ObjectiveNumerous epidemiological studies have been conducted to examine the prevalence and comorbidities of insomnia and document sleep duration, but a common limitation in many studies is the lack of use of agreed-upon definitions of insomnia, as well as insufficient statistical power to examine comorbid mental and physical disorders/conditions.AimTo examine the prevalence of insomnia operationalized according to formal DSM-5 criteria and differences in mean sleep duration across a wide range of mental and physical disorders, examining men and women separately.Materials and MethodsData stem from the SHoT study (Students’ Health and Wellbeing Study), a national survey of all college and university students in Norway. In all, 162,512 students aged 18–35 received an invitation to participate, of whom 50,054 students completed the internet-based survey (attendance rate: 30.8%). Insomnia was defined according to the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) criteria and sleep duration was calculated separately for weekdays and weekends. Self-reported mental and physical disorders/conditions were assessed using a pre-defined list modified to fit this age group. Pearson chi-squared tests were used to examine the prevalence of insomnia across the various mental and physical disorders/conditions in men and women separately, and log-link binomial regression analysis were used to calculate effect-sizes, adjusting for age.ResultsThe prevalence of insomnia in both sexes was significantly higher across all mental disorders compared with a healthy reference group. Among females, the prevalence of insomnia ranged from 61.3% for comorbid depression (adj. RR = 2.49, 95% CI: 2.40) to 83.3% for comorbid schizophrenia (adj. RR = 3.37, 95% CI: 2.61–4.35). For males, the insomnia prevalence ranged from 32.3% for comorbid autism/Asperger (adj. RR = 2.02, 95% CI: 1.39–2.92) to 74.2% for comorbid eating disorder (adj. RR = 4.51, 95% CI: 3.87–5.27). The overall prevalence of insomnia was also significantly higher across most physical conditions compared with the healthy reference group, although generally lower compared to the mental disorders. For females, the insomnia prevalence ranged from 25% for comorbid multiple sclerosis (not significant) to 65.4% for comorbid chronic fatigue syndrome/ME (adj. RR = 2.66, 95% CI: 2.44–2.89). For males, the insomnia prevalence ranged from 20% for both comorbid cancer and diabetes (not significant) to 74.2% for comorbid fibromyalgia (adj. RR = 4.35, 95% CI: 2.96–6.39). Similar patterns were observed for sleep duration, with a significantly shorter sleep duration for across many physical disorders, but especially mental disorders.ConclusionInsomnia and short sleep duration are strongly associated with a range of different disorders and conditions. Insomnia is most strongly associated with mental disorders, and physical conditions characterized by some level of psychological or psychosomatic properties.

Sleep Quality and Insomnia Severity among Italian University Students: A Latent Profile Analysis

“…On the whole, the identified insomnia subtypes recall symptoms clusters previously reported on the basis of objective and subjective sleep measures (in particular, the three clusters described by Crawford et al) [27][28][29]51] and expand them, highlighting the relevance of sleep quality components such as sleep medication use and daytime dysfunction. Additionally, in line with the previous literature [6,8,9], worse mental health and health-related quality of life were observed in the subtypes characterized by a higher insomnia severity in a seemingly gradient-like fashion. No differences between subgroups were found in healthrelevant behaviors (physical exercise, tobacco use, and alcohol consumption) and body mass index, whereas higher proportions of women were observed in the two moderate symptoms profiles (MI-MU and MI-SD).…”

“…Data were collected via an anonymous online survey delivered to students from Sapienza University of Rome through the Google Forms platform from March 2021 to June 2021. This procedure allows for rapidly collecting data from large samples using adapted versions of paper-and-pencil questionnaires and instruments and has been widely used in psychology and sleep research [ 4 , 8 , 29 , 39 ]. Participants took part in the study on a voluntary basis and provided online informed consent.…”

“…The first three items measure insomnia severity (difficulties in initiating and maintaining sleep and waking up too early), and the last four items assess sleep satisfaction, noticeability of the sleep problem to others, worry about the sleep problem, and sleep problem's interference with daily functioning. Four severity categories have been identified for the total score: no insomnia (score range 0-7), subthreshold insomnia (score range [8][9][10][11][12][13][14], moderate insomnia (score range [15][16][17][18][19][20][21], and severe insomnia (score range [22][23][24][25][26][27][28], and the original version of the instrument showed acceptable reliability, convergent validity with other subjective and objective sleep measures, and sensitivity to change after treatment. According to Morin et al [37], a cut-off of 10 maximizes sensitivity and specificity and is optimal for detecting insomnia cases in community samples, and thus a total score ≥ 10 was used in this study to select subjects reporting relevant insomnia symptoms.…”

“…Insomnia is a widespread sleep disorder, with an average prevalence rate of 10% [ 1 , 2 , 3 ] and even higher prevalence estimates reported after the COVID-19 outbreak [ 4 ]. Given its diffusion and its well-documented associations with adverse outcomes for both mental and physical health [ 5 , 6 , 7 , 8 , 9 , 10 ], insomnia is presently considered a relevant public health issue [ 2 , 11 ]. Interestingly, young adults [ 12 ] and university students in particular [ 13 ] report insomnia complaints more frequently in comparison with the general population, and according to several studies, the COVID-19 pandemic had a significant impact on this population’s sleep quality [ 14 , 15 ].…”

Worry about COVID‐19 as a predictor of future insomnia

“…Insomnia, the subjective perception of an inability to fall or stay asleep or early morning awakenings, occurs in 10%–30% of the population and can cause significant distress and impairment (Aernout et al, 2021 ; American Psychiatric Association, 2013 ; Dopheide, 2020 ; Ohayon, 2002 ; Sivertsen, Hysing, Harvey, & Petrie, 2021 ). Insomnia has significant deleterious consequences on physical health, including high blood pressure, congestive heart failure, diabetes, and stroke (Quan, 2009 ; Sofi et al, 2014 ).…”