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We are all familiar with the expression, the 'importance of a good night's sleep', and work in the field of circadian biology and sleep over the last 30 years has shown this to be true. Under normal conditions, our sleep and circadian rhythms are synchronised and prepare the body for the varied demands of the 24-hour rotation of the earth on its axis. This synchronisation (entrainment) of our sleep and circadian rhythms to the daily light/dark cycle depends upon our eyes. Eye healthcare providers are often consulted about screen use and its impact on ocular health, as well as the potential effects on sleep and circadian rhythms of viewing electronic devices at night. It is important to remember that the eye is not only an organ of vision, but also provides us with our sense of time, utilising specialised cells within the retina called photosensitive retinal ganglion cells (pRGCs). Exposing the pRGCs to light at the wrong time of the day may cause disruption of normal circadian rhythms and sleep. In this review, we give a brief overview of sleep as part of an individual's circadian biology with special emphasis on the role of the eye. We discuss the impact of blue light and medications on sleep and review the evidence for toxicity of short-wavelength light on the retina. We emphasise the importance of sleep for good ocular health, briefly discuss the impact of ocular disease on sleep and note the optimal timing of corticosteroids and prostaglandins. [ABSTRACT FROM AUTHOR]