The present study aimed to explore the interaction between work schedule (shift work versus non-shift work), genetic variability in SLC6A4 and insomnia symptoms.
Unconditional logistic regression models showed that the 5-HTTLPR genotype was significantly associated with insomnia, and >80% increased risk per S allele was observed.
Conversely, the serotonin transporter promoter polymorphism (5-HTTLPR) short allele was associated with neurovegetative symptoms such as insomnia, poor appetite and fatigue, but not sadness, worthlessness, or suicidal ideation.
We found the short (s-) allele of the 5-HTTLPR to be significantly more frequent in patients suffering from insomnia than in control individuals (47.1% vs. 39.9%: OR = 1.34).