A recent medical study has warned that sleeping on two pillows may be harmful to glaucoma patients, contrary to previous recommendations made by some doctors.
The study, published in the British Journal of Ophthalmology, found that raising the head at an angle of between 20 and 35 degrees using two pillows leads to increased intraocular pressure in two-thirds of glaucoma patients.
This result surprised the researchers, because some doctors had previously recommended that their patients sleep on several pillows to raise the head above heart level, based on their prior knowledge that sleeping on the back increases eye pressure.
The research team explains that raising the head unintentionally causes the neck to bend and the jugular veins to compress, preventing proper fluid drainage from the eyes. This theory was confirmed by a separate test that showed increased blood flow to the jugular veins in those who slept with their head elevated.
The researchers also noted that younger participants, under 44 years old, had higher eye pressure compared to older participants.
On the other hand, sleep specialists point out that using more than one pillow disrupts the natural alignment of the spine and neck, increasing the risk of back pain and discomfort. However, they sometimes recommend placing one pillow under the knees and another under the neck to alleviate back pain.
As for glaucoma patients, Dr. Thomas Johnson of Johns Hopkins University, who was not involved in the study, says that research is still inconclusive regarding the optimal sleeping position for them. He currently recommends that patients sleep in whatever position is most comfortable for them, given the lack of sufficient strong evidence from high-quality clinical research.
It should be noted that the study focused only on back sleeping positions and did not include side sleeping. Previous estimates suggest that differences in eye pressure may be more pronounced in those with advanced glaucoma or those with daytime low blood pressure.
