Tear film consists of three layers including outer lipid layer, aqueous layer and inner mucin layer.1,2 Lipid layer protects the aqueous layer of tear film from evaporation and mucin layer adhere the tear film to ocular surface. Aqueous layer, which is produced in lacrimal glands, is the most important in the health of ocular surface. Reduction of aqueous tear secretion results in the disruption of homeostasis at ocular surface and leads to dry eye syndrome.2 Dry eye syndrome is a common ocular surface disease associated with symptoms of eye discomfort, grittness and visual disturbance.1,2 Dry eye syndrome disrupts normal homeostasis at the ocular surface resulting in epithelial damage, epithelial cell apoptosis, loss of goblet cells, and squamous metaplasia.1-3 The changes and inflammation of ocular surface subsequently lead to tear instability, which causes an increased tear osmolarity and aggravates the inflammatory cascades. This leads to a vicious cycle.2 The regulation of tear film secretion is under neural and hormonal control.4 Dry eye syndrome has been associated with diverse and multiple causes, including depressive disorder, drugs, hormonal status, and systemic diseases.2 Sleep deprivation (SD) is known to cause profound impair¬ments in executive function and vigilant attention.5,6 It is also reportedly associated with autonomic and endocrine functioning7-9 and has been shown to increase blood pressure and stress hormone levels and decrease parasympathetic tone.10,11 Tear secretion is regulated by neurological factors and hormones,12 and so SD may have an effect on the tear film and ocular surface. However, only a few studies have evaluated the effect of sleep on the tear film and ocular surface.