Vol. 56, Issue 1, pp. 61-74 (2026)

Abstract

Billions of people worldwide suffer from sleep disorders and it is important to investigate how the lack of sleep or poor sleep quality affects the visual system. The primary aim of this study was to evaluate the influence of 1 night without sleep on the near point of convergence (NPC) and accommodation parameters in young adults. Twenty three young (mean age: 23.3 ± 1.68 years) adult subjects were recruited. NPC, accommodative facility, and amplitude of accommodation were measured after normal habitual sleep and after 1 night of sleep deprivation. Both the mean amplitude of accommodation and accommodative facility were significantly reduced after one night of sleep deprivation. With respect to NPC, both the break and recovery points of fusion were significantly receded after a sleep-deprived night. Our results showed that even 1 night without sleep may affect visual function associated with near vision tasks. Our findings suggest that sleep habits should be considered during optometric/ophthalmic examinations, especially when convergence and/or accommodation disorders are observed.