New genetic research suggests that childhood maltreatment and certain sleep problems share a bidirectional biological connection, with each influencing risk for the other.
Published in the European Journal of Psychotraumatology, the study used a technique called Mendelian randomization (MR) to probe the causal relationships between childhood maltreatment and six sleep-related phenotypes. Unlike traditional observational studies, MR leverages genetic variants as instrumental variables, making it far more resistant to confounding and reverse causation.
How the study worked
The researchers analyzed summary data from large European-ancestry genome-wide association studies (GWAS). For childhood maltreatment, they used a composite measure encompassing multiple abuse and neglect subtypes. For sleep, they examined six phenotypes: chronotype (morning vs. evening preference), daytime sleepiness, insomnia symptoms, sleep apnea, daytime napping, and sleep duration.
The primary analysis used inverse-variance weighted MR, with sensitivity checks via weighted median and MR-Egger methods. Multiple testing was corrected using the Benjamini-Hochberg procedure.
Key findings
In the forward direction (maltreatment affecting sleep), genetic liability to childhood maltreatment was significantly associated with three outcomes:
- Daytime sleepiness (OR 1.04, 95% CI 1.01-1.07)
- Insomnia symptoms (OR 1.08, 95% CI 1.01-1.15)
- Daytime napping (beta 0.07, 95% CI 0.03-0.09)
No significant links were found for chronotype, sleep apnea, or sleep duration.
In the reverse direction (sleep affecting maltreatment), genetic liability to daytime napping and insomnia symptoms was associated with higher childhood maltreatment liability. The authors caution, however, that reverse-direction findings may reflect shared genetic liability, gene-environment correlation, or reporting biases rather than a direct causal effect of adult sleep traits on childhood experiences.
What this means
The study provides some of the strongest genetic evidence to date that childhood maltreatment and sleep disturbances are intertwined at a biological level. The bidirectional signal is particularly notable: childhood adversity may disrupt sleep architecture, and poor sleep may amplify vulnerability to maltreatment or its reporting.
The effect sizes are modest, and the authors stress cautious interpretation. But the findings underscore the importance of assessing sleep health in children exposed to maltreatment, and of considering maltreatment history in patients presenting with insomnia or excessive daytime sleepiness.
Source: Zhang Z, Liu Y, Zhao Y. Bidirectional Mendelian randomization of childhood maltreatment and sleep-related phenotypes. Eur J Psychotraumatol. 2026;17(1):2692768. PMID: 42464740.