If the average American lives to be 78 years old, roughly a third of those years are spent lying on a mattress. Brandon Boor, a doctoral student at the University of Texas at Austin, studies air pollutants in the sleep microenvironment. In his most recent study, detailed in the journal Indoor Air, Boor covered a twin mattress with 225-thread-count sheets and seeded the bed with artificial dust as a proxy for the microorganisms, fungal spores and skin cells that routinely collect there. Volunteers dressed in clean suits then sat and spun around on the bed—all inside a sealed chamber—while instruments measured the particles that were kicked up and could be inhaled by the subjects. The concentrations are minute, measured in parts per million, but could affect us because we spend eight hours every day in “uncustomary proximity” to bedding and mattresses. The time spent under roofs in general has led the Centers for Disease Control and Prevention to conclude that health risks such as asthma and chronic heart problems from exposure to indoor air pollution may be greater than the risks from outdoor pollution. When it comes to bedtime, blankets and sleeping behaviors, among other factors, determine the extent to which “we are such stuff as dreams are made on.”