In 1984 Roger Ulrich went through ten years of recovery records at a hospital in suburban Pennsylvania. Twenty-three patients recovering from gallbladder surgery had a window facing a stand of trees, and 23 matched patients in similar rooms had a window facing a brick wall. The tree group left hospital sooner, took fewer strong painkillers and drew fewer negative comments in the nurses’ notes. Ulrich’s abstract states the direction of each difference without the figures, and the full paper is behind a paywall, so the entry below carries no figure.
The question has since moved into offices. In 2025 Sun Woo Chang and Stefano Schiavon asked 69 people to rate 15 window views inside one building. Views holding a lot of nature came out three times as satisfying as views holding little, and views through clear glazing twice as satisfying as views through a lowered blind. Chang and Schiavon also put a threshold on it: 35 per cent greenery or sky in the frame, with nothing in front of the glass.
Won Hee Ko and colleagues took the question somewhere less obvious in 2020. They put 86 people in a chamber held at 28 degrees, a little warmer than comfortable, and gave half of the sessions a window. The same room rated 0.3 scale points cooler with the window, the equivalent of 0.74 degrees, and 12 per cent more of the group called it comfortable. The air temperature was identical in both conditions.
The largest claims in this field come from a single experiment. In the autumn of 2019 a team led by Mohamed Boubekri ran 30 knowledge workers through a week in each of two identical offices in Durham, North Carolina, one glazed with electrochromic glass and one with a fixed roller shade. Wrist actigraphs recorded 37 minutes more sleep a night in the glazed office, and the workers scored 42 per cent higher on decision-making tests. A second paper from the same 30 people reported them 6.5 times as likely to say they were satisfied with the view. View Inc. paid for the study, manufactures the glass that was installed, and employs four of the authors. Both papers declare it.
That sleep result was not evenly spread. The people who slept least to begin with gained 52.8 minutes, while the good sleepers gained 18.1 minutes, and the second figure did not reach significance.
Light and a view arrive through the same opening, and few studies pull them apart. A.R. Joarder and A.D.F. Price managed it in 2012 by installing light sensors in the rooms of 263 patients recovering from coronary artery bypass surgery. Holding the outdoor view and the clinical measures constant, every extra 100 lux of daylight in the room shortened the stay by 7.3 hours.
Boubekri’s 42 per cent and 6.5 times are the largest figures here, and they come from 30 people working in glass made by the company that paid for the study.