Sleeping with a small part of the waist hanging, for the thinner people generally belong to a normal physiological phenomenon. The human waist corresponds to the lumbar spine, the lumbar spine itself is not a straight line, its physiological structure is a forward curvature, forming a physiological curvature. So thinner people lie flat on the bed when sleeping, the waist will have a small degree of suspension. If there is no obvious pain or other discomfort in the lower back, there is generally no need to deal with it. If you feel the feeling of loft when sleeping, caused by discomfort, you can place a thin soft pillow in the waist and the bed at the gap between the loft parts, appropriate to the waist a support, and then also in the bilateral knee below a soft pillow, or can be converted from a flat sleeper to a side sleeper, so that you can significantly reduce the feeling of discomfort. Lumbar discomfort should be timely consultation, follow the doctor’s instructions for treatment.