Sleep duration and depressive symptoms: a gene-environment interaction.

Area of Science:

• Behavioral genetics
• Psychiatry
• Sleep science

Background:

• Depressive symptoms are influenced by genetic and environmental factors.
• The role of sleep duration in modulating these influences is not fully understood.

Purpose of the Study:

• To investigate how sleep duration modifies genetic and environmental influences on depressive symptoms using quantitative genetic models.
• To examine the gene × sleep duration interaction in adult twins.

Main Methods:

• Analysis of data from 1,788 adult twins (894 same-sex pairs) from the University of Washington Twin Registry.
• Self-report measures of habitual sleep duration and depressive symptoms.
• Quantitative genetic interaction models to assess influences of additive genetic, shared environmental, and non-shared environmental factors.

Main Results:

• A significant gene × sleep duration interaction effect on depressive symptoms was identified.
• Heritability of depressive symptoms was 27% in the normal sleep range (7-8.9 hours/night).
• Heritability increased significantly at sleep duration extremes (5 hours/night: 53%; 10 hours/night: 49%).

Conclusions:

• Genetic contributions to depressive symptoms are elevated at both shorter and longer sleep durations.
• Sleep duration is a significant moderator of genetic influences on depression.