A Longitudinal Twin and Sibling Study of Associations between Insomnia and Depression Symptoms in Young Adults

Abstract

Study Objectives: To estimate genetic and environmental influences on the associations between insomnia and depression symptoms concurrently and longitudinally. Methods: Behavioral genetic analyses were conducted on data from the British longitudinal G1219 twin/sibling study. One thousand five hundred fiftysix twins and siblings participated at Time 1 (mean age = 20.3 years, SD = 1.76). Eight hundred sixty-two participated at Time 2 (mean age = 25.2 years, SD = 1.73 years). Participants completed the Insomnia Symptoms Questionnaire and the Short Mood and Feelings Questionnaire to assess symptoms of insomnia and depression respectively. Results: Genetic effects accounted for 33% to 41% of the variance of the phenotypes. The phenotypic correlations were moderate (r = 0.34 to r = 0.52). The genetic correlations between the variables were high (0.73-1.00). Genetic effects accounted for a substantial proportion of the associations between variables (50% to 90%). Non-shared environmental effects explained the rest of the variance and covariance of the traits. Conclusions: While genetic effects play a modest role in insomnia and depression symptoms separately, they appear to play a more central role in concurrent and longitudinal associations between these phenotypes. This should be acknowledged in theories explaining these common associations.

Dysfunctional beliefs about sleep and insomnia symptoms in early adulthood: A twin and sibling study

“…The total scale score was calculated by summing the responses and ranges from 0 to 24, with higher scores meaning more severe insomnia symptoms. Cronbach's alpha for the ISQ in the current sample was 0.87 (as reported in previous studies; Gregory et al, 2016;Schneider et al, in press).…”

Sleep quality, insomnia, and internalizing difficulties in adolescents: insights from a twin study

“…23,24,30,71 For insomnia we found a similar F o r R e v i e w O n l y 14 heritability estimate, and our results are also similar to those from studies of young and middle-aged adults. 26,29 For all measures of internalising symptoms, higher correlations were found between MZ as compared to DZ twins. Our results showed that genetic influences accounted for a significant proportion of the variance in these phenotypes.…”

“…[26][27][28][29] Regarding depression and anxiety, approximately 30-50% of the variance is typically explained by genetic factors. 9,[29][30][31][32] Studies examining the overlap between these variables have found that there is a substantial (sometimes complete) genetic overlap, with genetic correlations all above .5. 9,29,30,33 Adolescence is a period of great change for sleep.…”

“…9,[29][30][31][32] Studies examining the overlap between these variables have found that there is a substantial (sometimes complete) genetic overlap, with genetic correlations all above .5. 9,29,30,33 Adolescence is a period of great change for sleep. During this stage of life, bedtime typically becomes later and it can be more difficult to wake early.…”

Hypnotic drug risks of mortality, infection, depression, and cancer: but lack of benefit

“…The findings indicate that the association of suicides with hypnotic use cannot be entirely attributed to confounders with reverse causality, since the association of hypnotic usage with depression is known to be largely caused by the hypnotics 34 . Since the genetic influences promoting insomnia and depression appear highly correlated 103 , the associations both of depression and insomnia with mortality may be mediated through hypnotic drug consumption.…”