Researchers may have uncovered the mechanisms responsible for the sensation of skin tightness or softness following the use of topical treatments such as cleansers and moisturizers, according to a recent study published by Bennett-Kennett et al in PNAS Nexus. The study authors analyzed the effects of six cleansers and nine moisturizers on skin samples to determine how mechanical alterations to the outer surface of the skin translated into sensory perceptions. The researchers identified strong correlations between the perceptions up to 12 hours posttreatment and changes in neural stimulation from mechanoreceptors below the epidermis. They then compared their findings with responses from a trial in which 2,700 participants used either cleansers or moisturizers and were then asked about perceived sensations. When the skin is exposed to cleansers, the outermost layer is stripped of its moisture-holding lipids and the stratum corneum contracts; when moisturizers are then applied to the skin, the stratum corneum swells. The researchers suggested that the contracting and swelling forces may reach the mechanoreceptors, which relay signals to the brain that are interpreted as the sensation of skin tightness. The new findings may provide cosmetic companies with a framework to improve their formulations. In a companion press release on the findings from Stanford University, the study authors concluded: “This work provides a new understanding of how products affect the physical properties of our skin [and] … a whole new understanding of how to design those formulations.”