Does sleep position affect dry eye?

Effect of Sleep Position on the Ocular Surface


Alevi D, Perry HD, Wedel A, Rosenberg E, Alevi L, Donnenfeld ED.
 Cornea. 2017 Mar 1. doi: 10.1097/ICO.0000000000001167. [Epub ahead of print]

Abstract
PURPOSE:
Dry eye disease is a multifactorial disease with numerous well-documented risk factors. However, to date, sleep position has not been associated with this condition. After observing patients in our practice, we believe that the sleep position in some cases may significantly affect dry eye and meibomian gland dysfunction (MGD).
METHODS:
This is a single-centered, cross-sectional, noninterventional, institutional review board-approved, single-masked, nonrandomized study of 100 patients whose complaints were related to dry eye disease and a control group of 25 age-matched asymptomatic patients. Two questionnaires were used: one to analyze patients' sleep habits and the other to assess patients' Ocular Surface Disease Index. Dry eye severity was graded based on the MGD stage, fluorescein corneal staining and lissamine green staining, Schirmer 1 testing, tear osmolarity levels, and clinical examination.
RESULTS:
A statistically significant difference was shown with back sleeping compared with left side sleeping using lissamine green staining (analysis of variance, P = 0.005). The Ocular Surface Disease Index score was also found to be elevated in patients who slept on their right or left side (36.4 and 34.1, respectively) as opposed to back sleepers (26.7) with P < 0.05. There was no statistically significant correlation found between the sleep position and degree of MGD.
CONCLUSIONS:
In addition to current treatment, patients who sleep on their side or face down might see a reduction in dry eye and MGD if they change their sleep pattern to the supine position.

This is an interesting topic... While it doesn't attempt to address the causes, I would imagine it's all about greater exposure, especially if lids aren't fully closing. It would be interesting to know more about the extent to which lubricant and physical barrier protection improve this - comparatively - for the different sleep positions.