Abstract Background We observed that a dim. red light-emitting diode (LED) triggered by activity increased the circadian periods of lab mice compared to constant darkness. It is known that the circadian period of rats increases when vigorous wheel-running triggers full-spectrum lighting; however. spectral sensitivity of photoreceptors in mice suggests little or no response to red light. https://thegreensjunglebeautyshops.shop/product-category/silicone-funnel/