Investigating the links between adolescent sleep deprivation, fronto-limbic connectivity and the Onset of Mental Disorders: a review of the literature.

The importance of sleep for mental health has been known for some time. Although it was initially suggested that mental health conditions negatively impact sleep, it is now widely understood that this association is bidirectional. Adolescence is a period where people are at an increased risk of being sleep deprived largely due to a late shift in the circadian rhythm around puberty combined with early school start times. This combination may lead to adolescents being at an increased risk of mental health problems. Adolescence is also a period of continued brain development with white matter maturation continuing in the frontal brain regions throughout adolescence and into early adulthood. White matter development involves myelination of axons that link areas of grey matter and is integral for communication speed and efficiency. Studies have demonstrated that sufficient sleep is required for myelination to occur. The uncinate fasciculus (UF) is one of the last white matter tracts to be myelinated with this process occurring throughout adolescence and running between the amygdala in the limbic system and the orbitofrontal (OFC) and medial prefrontal cortices (mPFC). Recent studies have shown that connectivity between the amygdala and OFC is important for an individual's ability to exert top-down executive control over amygdala based automatic emotional responses to experiences perceived as threatening. The current literature review provides an overview of these mechanisms and concludes by proposing a model of adolescent sleep deprivation leading to potential life-long mental health issues through the moderating impact of reduced UF development.