Contrary to their expectations, researchers found sleeping with the head elevated may increase intraocular pressure (IOP) in patients with glaucoma.  

Exploring whether specific sleeping positions could help reduce IOP and function as an adjunctive strategy for nocturnal IOP management, 144 patients with glaucoma were enrolled in the Chinese study.  

Sleeping in a high-pillow position (two pillows, 20–35°) was associated with significantly elevated IOP, increased 24-hour IOP fluctuation and reduced ocular perfusion pressure (all p<0.001), compared with supine sleeping. Greater postural IOP fluctuation was observed in younger individuals (p=0.027) and patients with primary open-angle glaucoma (POAG) (p<0.001). Multiple regression analysis identified thicker central corneal thickness and the presence of POAG (vs normal-tension glaucoma) as positive predictors of larger IOP changes.  

Additionally, when compared to healthy individuals, ultrasonography revealed significant constriction of both internal and external jugular venous lumen in the high-pillow-position subjects (all p<0.001). This was accompanied by an increase in maximum blood flow velocity of the internal jugular vein (p=0.013).  

While calling for further studies to validate their preliminary findings, the authors concluded that patients with glaucoma may benefit from avoiding sleeping postures that induce jugular venous compression to mitigate postural IOP elevation.