The power of chronotype – an investigation into the genetic bases of diurnal preference and mental health

Wojtachnio, Monika (2022) The power of chronotype – an investigation into the genetic bases of diurnal preference and mental health. Masters thesis, University of East Anglia.

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Chronotype is a continuum of diurnal (time-of-day) preferences based on the underlying circadian rhythm. It stems from genetic differences and is modulated by the environment, especially light cues. Those on the late (evening) end of the spectrum often suffer from social jet-lag and can be more prone to mental health issues. This study confirms this pattern and provides further proof that although evening-type individuals often struggle, they also perform better on fluid intelligence tests than their morning-type peers. Here, we screened a population of university students aged 18-41 (n=100) using online questionnaires and investigated the genetic changes in the CRY1 gene of those who could attend a face-to-face meeting (n=32). Within this group, we uncovered a significant association of chronotype with age, depression, IQ, and positive affect. We also found three distinct SNPs (rs8192440, rs1056560, and rs8192441), out of which the rs8192440 polymorphism was the most frequent one, having been found in 76.7% of the studied population. None of these SNPs were found to be significantly associated with any of the studied variables. Despite this, we suggest further study of the rs8192440 and rs8192441 polymorphisms as they show promise regarding associations with mental health, chronotype, and sleep quality. Moreover, we show that the COVID-19-related lockdowns had a negative effect on the well-being, sleep quality, and self-perceived academic performance of students, while simultaneously allowing for a delay in chronotype and prolonged sleep duration. Overall, our data supports the idea that chronotype-based interventions such as delayed starting times at schools and workplaces for those with evening chronotype should be implemented to reduce the effects of social jet-leg. However, we suggest that this should be done in a structured fashion to avoid possible negative effects of delayed sleep phase such as a decrease in sleep quality and mental well-being, that could be observed during the COVID-19 pandemic.

Item Type: Thesis (Masters)
Faculty \ School: Faculty of Medicine and Health Sciences > School of Health Sciences
Depositing User: Chris White
Date Deposited: 23 Feb 2023 13:44
Last Modified: 23 Feb 2023 13:44

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