Early life stress linked to sleep anomaly

The findings of a new study suggest that stress in the early life leaves persistent molecular trace in the brain.

The doctoral study also found that early life onset of depression is characterized by changes in macro-and micro-architecture of sleep associated with the severity of depressive symptoms, said a press release of the University of Helsinki.

Early life stress, sleep disturbances and alterations in neuronal plasticity have been associated with depression, yet the relation between these factors and depression remain poorly understood, said Olena Santangeli of the University of Helsinki in her doctoral dissertation.

The study explored the interconnection between depression and sleep disturbances, starting from the early stage of development. Possible molecular mechanisms underlying this interaction were assessed using animal models. The investigation into sleep disturbances in early-onset depression in humans was performed in depressed adolescents.

To assess the effect of early life stress on sleep and possible mechanisms of this effect, she used cross-fostering in rats, i.e. pups were changed between mothers.

“Cross-fostered rats demonstrated negligible changes in behaviour. However, they showed profound changes in sleep architecture: duration and number of REM sleep episodes was significantly increased compared to controls. Moreover, cross-fostering led to persistent molecular changes in the brain areas crucial for sleep regulation,” said Santangeli.

To investigate sleep disturbances in early-onset depression, Santangeli studied sleep in depressed adolescent boys using polysomnography.

“The sleep of depressed boys was characterized by lower slow-wave activity, or SWA, and its slower rise during the course of first non-rapid eye movement sleep episode compared to healthy boys. The SWA dissipation through the night in depressed patients had flatter shape compared to healthy subjects. Moreover, a negative correlation between SWA dissipation and depression severity was detected,” Santangeli added.

Olena Santangeli will defend the doctoral dissertation entitled “Sleep and depression: developmental aspects and molecular mechanisms” at the Faculty of Medicine, University of Helsinki, on 20 April 2018.