The heritability of insomnia: A meta‐analysis of twin studies

Abstract

Twin studies of insomnia exhibit heterogeneity in estimates of heritability. This heterogeneity is likely because of sex differences, age of the sample, the reporter and the definition of insomnia. The aim of the present study was to systematically search the literature for twin studies investigating insomnia disorder and insomnia symptoms and to meta‐analyse the estimates of heritability derived from these studies to generate an overall estimate of heritability. We further examined whether heritability was moderated by sex, age, reporter and insomnia symptom. A systematic literature search of five online databases was completed on 24 January 2020. Two authors independently screened 5644 abstracts, and 160 complete papers for the inclusion criteria of twin studies from the general population reporting heritability statistics on insomnia or insomnia symptoms, written in English, reporting data from independent studies. We ultimately included 12 papers in the meta‐analysis. The meta‐analysis focussed on twin intra‐class correlations for monozygotic and dizygotic twins. Based on these intra‐class correlations, the meta‐analytic estimate of heritability was estimated at 40%. Moderator analyses showed stronger heritability in females than males; and for parent‐reported insomnia symptoms compared with self‐reported insomnia symptoms. There were no other significant moderator effects, although this is likely because of the small number of studies that were comparable across levels of the moderators. Our meta‐analysis provides a robust estimate of the heritability of insomnia, which can inform future research aiming to uncover molecular genetic factors involved in insomnia vulnerability.

Comparison of the Differences in State-Trait Anxiety Inventory Scores and Insomnia Histories between Monozygotic and Dizygotic Twins: A Cross-Sectional Study Using KoGES HTS Data

“…Insomnia was not highly coincident in monozygotic twins compared to dizygotic twins in this study. In twin studies based on young populations, the heritability of insomnia has been suggested with mixed results [ 6 , 8 , 21 , 22 ]. In a meta-analysis study, the correlation of insomnia was higher in monozygotic twins than in dizygotic twins (0.37, 95% CI = 0.31–0.43 for monozygotic twins and 0.15, 95% CI = 0.12–0.18 for dizygotic twins) [ 21 ].…”

“…Multiple candidate genes for gene–environmental interactions in anxiety have been suggested [ 5 ]. Insomnia is one of the associated factors for anxiety, which also has heritability [ 6 , 7 , 8 ]. In a meta-analysis of twin studies, approximately 40% of heritable factors contributed to the occurrence of insomnia [ 6 ].…”

“…Insomnia is one of the associated factors for anxiety, which also has heritability [ 6 , 7 , 8 ]. In a meta-analysis of twin studies, approximately 40% of heritable factors contributed to the occurrence of insomnia [ 6 ]. In addition, it was supposed that there are some overlapping heritable factors of insomnia with anxiety [ 8 ].…”

Twin Studies in Sleep Medicine: A Review

“…They did not find significant differences in heritability between various insomnia symptoms, but noted there was a broad range between studies for difficulty initiating sleep (0-79%) and difficulty staying asleep (25-42%), with fewer studies evaluating early morning awakenings (34-35% in one study) and awakening tired (26% in one study). 14 Studies looking at pre-sleep arousal and sleep reactivity have also found substantial genetic overlap with insomnia, indicating possible enhanced vulnerability to insomnia occurring with these symptoms. A longitudinal twin and sibling study found a strong correlation between genetic influences on overall pre-sleep arousal and insomnia symptoms (genetic correlation = 0.88), as well as between cognitive pre-sleep arousal, somatic pre-sleep arousal, and insomnia symptoms (genetic correlations 0.93 to 1).…”

“…11 Numerous twin studies have identified the heritability, gene-environment interactions, and gene-environment correlations for both normal and pathologic sleep phenotypes. [12][13][14][15][16][17] Twin studies have also examined associations between sleep phenotypes and other health-related traits and disorder phenotypes, [18][19][20][21][22] many of which either impact sleep or are impacted by sleep. This provides an important body of work highlighting the complexity of genetic and environment interplay between sleep and health.…”