In this latest video from MedCram, Dr. Seheult discusses a newly published study that is drawing serious attention to the potential role of infrared light in the intensive care unit (ICU). When viewed alongside decades of research on sunlight and hospital outcomes, these findings suggest that light—particularly red and near-infrared wavelengths—may play a much more significant role in healing than previously understood.
A July 2025 paper from the Glen Jeffery group, published in Nature Scientific Reports, demonstrated that infrared light in the 850–880 nanometer (nm) range can penetrate completely through the human body. Using highly sensitive detection equipment, researchers showed that near-infrared light passes through tissues, including bone, is absorbed by water and biological structures, and produces systemic effects. They even measured improvements in vision, which is particularly notable because the retina contains one of the highest concentrations of mitochondria in the body.
What is the abscopal effect?
The study also demonstrated what is known as the abscopal effect, meaning that light applied to one area can produce biological changes in distant organs. This challenges the older assumption that light primarily affects the skin or circadian rhythms and instead suggests that infrared light may influence cellular function throughout the body.
Can light affect hospital outcomes?
The concept that light affects hospital outcomes is not new. For decades, research has shown that access to sunlight and natural views reduces hospital length of stay and, in some cases, mortality. Postoperative patients with natural window views have been shown to recover faster than those facing brick walls. Cardiac ICU patients placed in sunny rooms have demonstrated lower mortality and shorter stays compared to those in dim rooms. Psychiatric inpatients assigned to east-facing rooms with morning sunlight have experienced reductions in length of stay by several days.
Similar findings have been observed across orthopedic wards, surgical ICUs, sepsis units, and general inpatient settings, with consistent trends showing that increased daylight exposure correlates with shorter hospitalization periods. These studies span thousands of patients across multiple countries and clinical contexts, reinforcing the idea that light exposure is not merely aesthetic but biologically meaningful.
The most compelling recent addition to this body of research was published in May 2025 and examined photobiomodulation therapy in ICU patients. This randomized, triple-blind, sham-controlled trial enrolled 60 medical and surgical ICU patients in Brazil. Participants received daily 15-minute sessions of red light at 635 nm and near-infrared light at 880 nm delivered through a light blanket placed over the limbs. The control group received an identical device that was not activated, and the study was rigorously designed so that patients, outcome assessors, and analysts were all blinded to group assignments.
There was no heat generated and no adverse events reported. The primary outcome was ICU length of stay, and the results were striking. Patients receiving photobiomodulation therapy had an average ICU stay of 79 hours compared to 111.7 hours in the sham group, representing approximately a 30 percent reduction that was statistically significant.
Secondary outcomes were equally important. Patients in the treatment group demonstrated improved mobility, greater global strength, and stronger hand grip. This is clinically meaningful because many ICU patients recover from their acute illness yet remain too weak to return home, requiring transfer to rehabilitation facilities. Improving muscle strength during ICU care directly supports functional recovery and earlier discharge.
Can light affect hospital finances?
From an economic standpoint, these findings are highly relevant. In the United States, hospitals are reimbursed through Diagnosis-Related Groups (DRGs), meaning they receive a fixed payment for a given diagnosis regardless of how long the patient remains hospitalized. Longer stays increase hospital costs, particularly in the ICU where staffing, monitoring, and equipment expenses are substantial. A 30 percent reduction in ICU length of stay represents significant cost savings.
This creates a rare alignment of incentives: patients recover faster, hospitals reduce expenditures, and no meaningful safety concerns have been identified. It is uncommon to see an intervention that is low risk, relatively simple to administer, and potentially transformative in both clinical and financial terms.
Why is light even being looked at?
One important question is why light would produce these effects in the first place. Modern indoor environments are largely deficient in infrared light. Low-emissivity (low-E) glass commonly used in homes, offices, and hospitals blocks much of the infrared spectrum. While visible light enters buildings, the infrared wavelengths abundant in natural sunlight and strongly reflected by green vegetation are significantly reduced indoors.
Leaves, trees, and grass reflect substantial amounts of infrared light, which may help explain why living near green spaces has been associated with lower rates of chronic disease, reduced cardiovascular mortality, and improved overall health outcomes. Historically, healthcare institutions understood the value of sunlight. Facilities such as the Battle Creek Sanitarium were intentionally designed to maximize patient exposure to natural light. Tuberculosis sanatoriums across Europe and North America emphasized outdoor air and full-spectrum sunlight as foundational elements of therapy. Modern architectural priorities focused on energy efficiency may have inadvertently removed an important biological input.
When we combine the new evidence showing systemic penetration of infrared light, the randomized ICU photobiomodulation trial demonstrating a 30 percent reduction in ICU stay, and decades of research linking natural light exposure to improved hospital outcomes, the case becomes increasingly compelling. Although the recent ICU study was relatively small and conducted at a single center, its rigorous triple-blind design and statistically significant findings warrant serious attention. Larger multicenter trials would help confirm and expand upon these results, but the low-risk profile and ease of implementation make this an intervention that forward-thinking hospitals could begin exploring now. Photobiomodulation therapy could be incorporated into ICU rehabilitation protocols with minimal disruption and potentially substantial benefit.
For many years, medicine has largely viewed light through the lenses of vitamin D production and circadian rhythm regulation. Emerging research now suggests that red and near-infrared light may directly enhance mitochondrial function and systemic physiology. The idea that light is a fundamental biological input rather than merely illumination is gaining scientific support. As evidence continues to accumulate, restoring exposure to therapeutic wavelengths—whether through architecture, outdoor access, or targeted photobiomodulation—may become an important component of modern medical care.
References
Photobiomodulation therapy (red/NIR LEDs) reduced the length of stay in intensive care unit and improved muscle function: A randomized, triple-blind, and sham-controlled trial (Journal of Biophotonics)
https://pmc.ncbi.nlm.nih.gov/articles/PMC…
Longer wavelengths in sunlight pass through the human body and have a systemic impact which improves vision (Nature Scientific Reports)
https://www.nature.com/articles/s4159…
The Guy Foundation (YouTube)
https://www.youtube.com/@theguyfoundation
Optimal Health & Immunity (MedCram)
https://www.medcram.com/collections/health