The relationship between the morningness-eveningness questionnaire and incident cancer: A historical clinical cohort study.

OBJECTIVE: We conducted a retrospective cohort study to explore the relationship between chronotype measured by the total Morningness-Eveningness Questionnaire (MEQ) score and incident cancer. METHODS: We used clinical and provincial health administrative data on consecutive adults who underwent a Level 1 Polysomnography (PSG) and completed the MEQ between 2010 and 2015 in an academic hospital (Ontario, Canada) and were cancer-free at baseline. Cancer status was derived from the Ontario Cancer Registry. Individuals were followed until death or March 31, 2020. We used multivariable Cox cause-specific regressions to address the research objective. RESULTS: Of 3,004 individuals, 1,781 were analyzed: a median age of 54 years (IQR: 40-64) and 838 (47.1%) men. The median total MEQ score was 63 (IQR: 55-69); 61 (3.4%) were classified as evening (≤41), 536 (30.1%) as intermediate (42-58), and 1,184 (66.5%) as morning chronotypes (≥59). Over a median of 7 years (IQR: 5-8), 120 (6.7%) developed cancer. A U-shape relationship was found between the total MEQ score and an increased hazard of incident cancer, controlling for PSG measures of sleep apnea severity and sleep architecture, demographics, and comorbidities. Compared to the median of 63.0, a total MEQ score greater or less than the median was associated with an increased hazard of incident cancer, with the largest effect for those with a total score ≥76 (e.g., HR of a MEQ total score of 78 vs. 63: 2.01, 95% CI: 1.09-3.71). CONCLUSION: The U-shaped curve may reflect deviations from a standard circadian tendency, which may stress biological systems and influence malignancy risk.

Impact of sleep chronotype on in-laboratory polysomnography parameters.

Morningness-eveningness preference, also known as chronotype, is the tendency for a person to sleep during certain hours of the day and is broadly categorised into morning and evening types. In-laboratory polysomnography (iPSG) is the gold-standard to assess sleep, however, an individual's chronotype is not accounted for in current protocols, which may confound collected sleep data. The objective of our study was to assess if chronotype had an association with sleep physiology. Patients who completed the diagnostic iPSG and the Morningness-Eveningness Questionnaire (MEQ), which categorises patients into morning type, neither or evening type, were assessed. Multivariable linear regression models were used to assess if chronotype was associated with sleep quality, duration, and physiology during iPSG. The study sample included 2612 patients (mean age of 53.6 years, 48% male) recruited during 2010-2015. Morning type, compared with neither type, was significantly associated with an increase in total sleep time and rapid eye movement (REM) sleep, and a decrease in sleep onset latency and the arousal index. Evening type, compared with neither type, was significantly associated with a decrease in total sleep time, sleep efficiency, and REM sleep, and an increase in sleep onset latency and wake after sleep onset. Additionally, iPSG lights out time was significantly different between the different chronotypes. Overall, a morningness chronotype was associated with favourable sleep quality and duration while an eveningness chronotype was associated with reduced sleep quality. Our study quantifies the association of chronotype with iPSG metrics and suggests that laboratory protocols should consider chronotype in their evaluations.