a set of sheets includes an upper sheet with a top panel and a lower sheet with a bottom panel . in conjunction , the upper and lower sheets are sized , structured and configured to enclose a mattress . a waterproof panel is positioned between the upper sheet and the top of the mattress to protect the mattress from damaging exposure to moisture and liquids , including bodily fluids . in several embodiments , the upper sheet and waterproof panel are removable for washing and changing thereof while the lower sheet remains fitted to the mattress , thereby avoiding the need to lift or move the mattress when changing the sheets . the waterproof panel may be independently removable to selectively control air permeability of the sheets , and particularly the upper sheet . in a further embodiment , a minor waterproof panel is removably attachable in covering relation to a portion of the top surface of the upper sheet to protect the upper sheet and mattress from becoming soiled , and thereby extending the period of time between laundering and changing of the set of sheets .