Higher head elevation during sleep may be associated with higher IOP, study suggests

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A clinical study published in the British Journal of Ophthalmology examined whether a commonly used high-pillow sleeping position affects intraocular pressure (IOP) in patients with glaucoma during nocturnal periods. The findings suggest that elevating the head with 2 regular pillows during sleep is associated with higher IOP, greater 24-hour IOP fluctuation, and reduced ocular perfusion pressure (OPP) compared with the supine position.

The first author of the study is Tong Liu, PhD, of the Eye Center at Zhejiang University in Hangzhou, China.

The study included 144 patients with glaucoma or ocular hypertension who underwent 24-hour IOP monitoring between October 2023 and April 2024. Measurements were taken every two hours using a rebound tonometer, with nocturnal assessments performed first in the supine position and then after elevating the head by 20° to 35° using 2 pillows. Patients continued their prescribed IOP-lowering treatments throughout the monitoring period.

Overall, 66.7% of patients experienced an increase in IOP when moving from the supine to the high-pillow position, with a mean rise of 1.61 mmHg. Mean IOP was significantly higher in the high-pillow position than in the supine position, and 24-hour IOP fluctuation was also greater. OPP was significantly lower in the high-pillow position.

“Notably, previous investigations have shown that semi-reclining positions (achieved via wedge pillows or elevated bedheads) resulted in significant IOP reduction compared with the supine position,” the study authors stated.2,3 “This discrepancy may be attributed to distinct effects on cervical biomechanics. The use of a wedge pillow to elevate the upper body promotes cervical extension, whereas adopting a high-pillow position primarily alters head posture, resulting in neck flexion.”

Subgroup analyses showed that younger patients had greater postural IOP changes than older patients. Patients with primary open-angle glaucoma (POAG) demonstrated larger IOP increases than those with normal-tension glaucoma (NTG). Multivariate regression analysis identified thicker central corneal thickness and the presence of POAG as significant predictors of greater postural IOP fluctuation.

To explore potential mechanisms underlying these findings, the researchers conducted a supplementary ultrasonography study in 20 healthy volunteers. Jugular vein imaging showed that, compared with the supine position, the high-pillow position was associated with smaller diameters and cross-sectional areas of both the internal and external jugular veins, along with increased internal jugular vein blood flow velocity. These findings suggest mechanical compression of the jugular veins during head elevation.

The authors propose that neck flexion in the high-pillow position may impede venous outflow, potentially affecting aqueous humor drainage and contributing to increased IOP. They note that this posture differs biomechanically from semi-reclined positions achieved with wedge pillows or adjustable beds, which have previously been associated with reduced IOP.

The study concludes that sleeping with the head elevated using regular pillows may be associated with less favorable nocturnal IOP and OPP profiles in glaucoma patients. The authors suggest that avoiding sleeping positions that induce jugular venous compression may represent a simple adjunctive consideration for long-term IOP management.

“While this 15-degree range introduced an element of variability, this methodological approach offers more clinically relevant insights for daily IOP management in everyday practice,” the study authors stated. “Future research may evaluate postural IOP changes across a broader spectrum of elevation angles to refine these findings.”

References:

1. Liu T, Hu M, Liu X, et al. Association of high-pillow sleeping posture with intraocular pressure in patients with glaucoma. Brit Journ Ophthalmol. 2026. doi:10.1136/bjo-2025-328037

2. Buys YM, Alasbali T, Jin Y-P, et al. Effect of sleeping in a head-up position on intraocular pressure in patients with glaucoma. Ophthalmology. 2010;117:1348–51. doi:10.1016/j.ophtha.2009.11.015

3. Lam CTY, Trope GE, Buys YM. Effect of head position and weight loss on intraocular pressure in obese subjects. J Glaucoma. 2017;26:107–12. doi:10.1097/IJG.0000000000000573