Sunlight may help keep you healthy even when you’re indoors. Cleveland Clinic Wellness described a recent study in which researchers filled miniature rooms with dust from nearby homes. The researchers then looked at how different amounts of sunlight affected the number of bacteria inside the rooms. “After 90 days, the darker mini-rooms contained twice as much bacteria as the rooms exposed to sunlight and included bacteria linked to respiratory diseases,” the clinic reports. “The bacteria populations in the sunlight-exposed rooms resembled those of outdoor air.” So if you want to breathe clean, it can’t hurt to keep the blinds up!