Zijnge, Sjoerd (2026) Does circadian rhythm dysregulation contribute to the etiology and development of bipolar disorder? Bachelor's Thesis, Biology.
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Abstract
Bipolar disorder (BD) is a chronic psychiatric disorder characterized by recurrent episodes of mania, hypomania and depression. Although the disorder is highly heritable, the biological mechanisms underlying its development and progression remain incompletely understood. In recent years, increasing attention has been directed toward the circadian system, which regulates sleep-wake cycles, hormone secretion and numerous physiological processes involved in mood regulation. This thesis aimed to evaluate whether circadian rhythm dysregulation contributes to the etiology and development of bipolar disorder. To address this question, current literature on sleep and rhythm disturbances, chronotype, biological markers of circadian function and circadian clock genes was reviewed. Evidence from multiple studies demonstrated that sleep-wake disturbances, evening chronotype and altered melatonin responsiveness are frequently observed in individuals with BD. Importantly, several of these abnormalities persist during euthymic periods, suggesting that they may represent stable characteristics of the disorder rather than solely consequences of active mood episodes. Genetic studies further identified associations between circadian clock genes and BD, while animal models demonstrated that disruption of circadian genes can induce behavioral changes resembling aspects of mania. Despite these findings, important limitations remain. Much of the available evidence is cross-sectional, making it difficult to determine whether circadian abnormalities precede disease onset or emerge during illness progression. Consequently, definitive conclusions regarding causality cannot yet be drawn. Overall, the current literature supports a contributory role of circadian rhythm dysregulation in bipolar disorder. Rather than functioning solely as a cause or consequence of illness, circadian dysfunction likely interacts with genetic vulnerability and environmental factors throughout both the development and clinical course of BD. Future longitudinal research will be essential to clarify the causal relationship between circadian dysregulation and bipolar disorder and to determine its potential as a target for prevention and treatment.
| Item Type: | Thesis (Bachelor's Thesis) |
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| Supervisor name: | Jorna, L.M. and Havekes, R. |
| Degree programme: | Biology |
| Thesis type: | Bachelor's Thesis |
| Language: | English |
| Date Deposited: | 05 Aug 2026 06:54 |
| Last Modified: | 05 Aug 2026 06:54 |
| URI: | https://fse.studenttheses.ub.rug.nl/id/eprint/37486 |
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