Chronobiology internationalSep 1, 2026

Changes in daily biological rhythms over 2 years in college students with and without nearsightedness

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Sep 2, 2026

Abstract

A total of 450 college students, including 353 with myopia, were studied to assess circadian rhythm changes over 2 years.

Myopic students initially had later bedtimes, earlier wake-up times, and lower scores on the Morningness-Eveningness Questionnaire compared to non-myopic students.
During the 2-year follow-up, both groups experienced earlier bedtimes, later wake-up times, and increased Morningness-Eveningness scores.
Only myopic students exhibited a 45-minute delay in dim-light melatonin onset (DLMO) after 2 years.
Analysis indicated that myopic individuals consistently had later bedtimes and earlier wake-up times after adjusting for potential confounders.
These observations may highlight significant circadian rhythm changes associated with myopia.

Simplified

This study aimed to characterize and compare the differences in circadian rhythm changes during 2 years between college students with myopia and non-myopia based on a longitudinal cohort study. Wake-up time and bedtime were obtained through a self-administered questionnaire. Chronotype was assessed using the reduced Morningness-Eveningness Questionnaire (rMEQ). Circadian rhythm timing was determined by dim-light melatonin onset (DLMO), measured through hourly saliva collection from 21:00 to 01:00. A total of 450 college students (146 [32.4%] males) with a mean age of 18.65 ± 1.05 years were included, of whom 353 (78.4%) students had myopia. Compared with non-myopic individuals, myopic students slept later, woke up earlier, and exhibited lower rMEQ scores at baseline. Over the 2-year follow-up, both groups showed significantly earlier bedtimes, later wake-up times, and higher rMEQ scores. Only myopic students demonstrated a 45-minute delay in DLMO after the 2-year follow-up. After adjusting for potential confounders, linear mixed-effects models showed that myopic individuals had later bedtimes and earlier wake-up times. These findings indicate significant circadian rhythm changes in individuals with myopia, suggesting the potential of targeted sleep rhythm interventions on preventing myopia.

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Changes in daily biological rhythms over 2 years in college students with and without nearsightedness

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