Association Between Childhood Behavioral Problems and Insomnia Symptoms in Adulthood

Key Points Question Are childhood behavioral problems associated with self-reported insomnia symptoms in adulthood? Findings In this population-based cohort study, there was a significant association between childhood behavioral problems measured using the Rutter Behavioral Scale at 5, 10, and 16 years of age and self-reported insomnia symptoms at 42 years of age. Meaning There was an increased risk of self-reported insomnia symptoms at 42 years of age among those who had moderate and severe behavioral problems during childhood, compared with those without behavioral problems during childhood.

1. Very restless, often running about or jumping up and down 2. Is squirmy or fidgety 3. Often destroys own or others property 4. Frequently fights with other children 5. Not much liked by other children 6. Often worried, worries about many things 7. Tends to do things on own -rather solitary 8. Irritable, is quick to fly off the handle 9. Often appears miserable, unhappy, tearful or distressed 10. Sometimes takes things belonging to others 11. Has twitches, mannerisms or tics of the face or body 12. Frequently sucks thumb or fingers 13. Frequently bites nails or fingers 14. Is often disobedient 15. Cannot settle to anything for more than a few moments 16. Tends to be fearful or afraid of new things or new situations 17. Is fussy or over-particular 18. Often tells lies 19. Bullies other children At 5 and 16 years, three responses (0=does not apply; 1=applies somewhat; 2=certainly applies) were summed up to give an overall score ranging from 0 to 38. At 10 years, a visual analogue scale system that ranges from 0 (does not apply) to 100 (certainly applies) was used.

Outcome
We used questions related to insomnia at 42 years because similar questions were not available in the previous follow ups. Questions and responses that were used to assess insomnia symptoms at 42 years are the following:

A) Difficulty initiating sleep (DIS)
During the last four weeks, how long did it usually take for you to fall asleep?

B) Difficulties maintaining sleep (DMS)
During the past four weeks, how often did you awaken during your sleep time and have trouble falling back to sleep again?
• None of the time When a participant had DIMS and not felt rested on waking (DIMS plus)

Covariates
At age 5 and 16 years, data on sleep difficulty of child was collected using maternal self-completed questionnaire, with a question "Does your child have any sleeping difficulties?" and responses were "no", "yes-mild", "yes-severe", yes-Not Elsewhere Classified". We combined all "yes" responses together as a positive answer. At 10 years, parent was asked whether a child has sleep difficulty with responses of "yes" and "no".
At 5, 10 and 16 (combined for both parents) years, maternal and paternal educational status was classified as no qualification, trade/vocational/certificate, degree and above, and other.
There were six social class categories, ranging from social class I (lowest class) to SC V (highest, professional). At 5, 10 and 16 years, we recategorized social class of mothers and fathers (combined at 5 years and separately at 10 and 16 years) into three: I & II; III non-manual & III manual and IV & V.
At 42 years, marital status was categorized into single, married/partnered, and divorced/separated/widowed. We classified social class as: I & II; III non-manual & III manual and IV & V [I, professional; II, managerial and Technical; III non manual; III manual; IV partly skilled; V unskilled]. Education qualification was categorized into five levels based on National Vocational Qualification Scale (NVQ). NVQs were work-based awards in England, Wales and Northern Ireland that given through assessment and training. We categorized smoking into non-smoker, current smoker and ex-smoker. Alcohol consumption frequency was categorized as never, monthly or less, 2-4 times a month, 2-3 times a week and 4 or more times a week. Physical activity was assessed based on frequency of different sport activities in 12 months prior to data collection and classified as never, less often, 2-3 times, once a week, 2-3 days a week, 4-5 days a week and every day.
We used body mass index from age 10, 16, 26, 30, 34 and 42 years and used group-based trajectory model 2 to assess pattern of body mass index trajectories. Body mass index was calculated from measured and self-reported weight and height. Details of data collection on BMI is described elsewhere. 3 Perceived health status was asked at 42 years of age with response categories of "excellent", "very good", "Good", "fair" and "poor".

Statistical analysis
In the joint classification analysis, we categorized children with moderate and severe behavioral problems together.
We used "paramed" 4,5 command in Stata to determine the indirect effect of childhood behavioral problem on adulthood insomnia symptoms that was mediated though childhood sleep difficulty (categorical variable) and mental health assessed by the Warwick-Edinburgh Mental Wellbeing Scale (continuous). In this analysis, we determined controlled direct effect (CDI), natural indirect effect (NDI), total effect (TE) and proportion of mediation (PM). Because "mi estimate" is not supported by paramed, we used "cmdok" option in the command.
We performed multiple imputation using 30 imputed data as we did not find estimate differences beyond 30. We combined DIMS with one of the following day time symptoms: irritability, tiredness, depression or nervousness. These symptoms are were asked using the following questions: Tiredness: "Do you feel tired most of the time? "yes/no" Irritability: 'Are you easily upset or irritated? "yes/no" Depressed: "Do you often feel miserable or depressed?" "yes/no" Nervousness: Does every little thing get on your nerves and wear you out?" "yes/no" These questions were not asked in the context of exploring the consequences of daytime feelings of insomnia. Therefore, we did not include in the main analysis. In addition, some of these symptoms are part of the Rutter Behavioural Scale, which they could persist during adulthood and may not be related to insomnia.