Nocturnal Dry Eye Causes and Mechanisms

Primary Mechanisms During Sleep

Incomplete eyelid closure (lagophthalmos) during sleep is a major cause of nocturnal dry eye, allowing continuous tear evaporation and exposure of the ocular surface throughout the night, according to the American Academy of Ophthalmology 1, 2
Eyelid malposition, exophthalmos, and thyroid-associated ocular disease prevent complete lid closure during sleep, contributing to dry eye, as reported by the American Academy of Ophthalmology 1, 2, 3
Neuromuscular disorders affecting eyelid function (Parkinson disease, Bell's palsy) impair proper lid closure and blinking mechanisms, leading to dry eye, as noted by the American Academy of Ophthalmology 1, 2, 3

Tear film instability is more common than pure aqueous deficiency and represents the primary pathophysiologic mechanism, according to the American Academy of Ophthalmology 4, 5

Sleep disorders themselves are associated with dry eye disease, with studies showing 17.5% prevalence of dry eye among patients with sleep disorders, as reported by the American Academy of Ophthalmology 4
Use of sedative-hypnotic medications for sleep disorders may be associated with dry eye development, as noted by the American Academy of Ophthalmology 4, 5

Antihistamines, antidepressants, and antianxiety medications reduce tear production and worsen overnight dryness, according to the American Academy of Ophthalmology 4, 5, 6
Anticholinergics and diuretics decrease tear secretion through disruption of efferent cholinergic nerves, as reported by the American Academy of Ophthalmology 4, 5, 6
Systemic retinoids (isotretinoin) significantly reduce tear production, as noted by the American Academy of Ophthalmology 4, 5, 6

Low humidity environments from air conditioning or heating increase evaporative loss during sleep, according to the American Academy of Ophthalmology 5, 6
Direct air flow to the face during sleep (fans, HVAC vents) accelerates tear evaporation, as reported by the American Academy of Ophthalmology 6

Sjögren's syndrome causes destruction of lacrimal gland tissue, eliminating reflex tearing and severely reducing tear production during all hours including sleep, as noted by the American Academy of Ophthalmology 2, 3, 5
Diabetes mellitus, particularly with poor metabolic control, is associated with increased dry eye prevalence, according to the American Academy of Ophthalmology 4, 5
Autoimmune thyroid disease and rheumatoid arthritis increase dry eye risk, as reported by the American Academy of Ophthalmology 4, 5

Rosacea can be difficult to diagnose in darker skin tones and children, but significantly exacerbates nocturnal dry eye through meibomian gland dysfunction, as noted by the American Academy of Ophthalmology 6
In younger patients and males with nocturnal dry eye, suspect underlying systemic or local conditions rather than age-related changes, according to the American Academy of Ophthalmology 1, 2, 3
Extended screen time before bed reduces blink rate and worsens overnight symptoms by destabilizing the tear film prior to sleep, as reported by the American Academy of Ophthalmology 1, 2, 3, 5
Frequent use of preserved eye drops (>4 drops daily) causes corneal epithelial breakdown that manifests as morning dryness, according to the American Academy of Ophthalmology 5, 6

Compromised homeostasis of the ocular surface microenvironment contributes to dry eye, as noted by the American Academy of Ophthalmology 4, 6