Irregular sleep patterns during adolescence may alter how the brain responds to prenatal risk factors linked to conditions such as schizophrenia and autism, new research in mice suggests.
The study found that circadian rhythm disruption – when the body’s internal clock is out of sync – can influence memory, anxiety, social behaviour and gene activity in brain regions associated with these disorders.
Lead author Tara Delorme conducted the study as a PhD student at the Douglas Research Centre.
She said: “While more research is needed, our findings suggest that people exposed to multiple risk factors may need to be especially mindful of their daily rhythms.”
Researchers also examined the combined impact of this disruption and exposure to prenatal infection.
Maternal infections during pregnancy, such as flu, are known to increase a child’s risk of developing brain disorders later in life.
Disrupted sleep patterns during adolescence – often indicating misaligned circadian rhythms – are also associated with these conditions.
In the study, researchers exposed mice to either a simulated prenatal infection, constant light during adolescence to disrupt circadian rhythms, both factors together, or neither.
Each factor produced some behavioural or genetic effects independently, but the combination resulted in changes that were not always as expected.
Researchers had expected the combined effects to be more severe.
Senior author Nicolas Cermakian is professor in McGill’s department of psychiatry.
He said: “We assumed the effects would be additive.
“But in some cases, disruption of biological rhythms actually reduced the impact of prenatal infection. That suggests these factors may interact in unexpected ways.”
The researchers focused on adolescence as it is a sensitive period of brain development, when the brain undergoes major changes.
Cermakian said: “Adolescents are vulnerable.
“Their internal clocks tend to run later than the rest of the population, but school still starts early.
“On top of that, evening exposure to screens and artificial light can further delay their biological rhythms, leading to what we call social jet lag.”
Social jet lag refers to the mismatch between the body’s internal clock and external schedules, and has been linked to a range of health concerns.
The team is now investigating the gene changes observed in mice to better understand how they may relate to human brain development.
