This study aims to investigate the measurement performance on different sensor deployment and to determine the optimal position for monitoring heart rate (HR) and respiration rate (RR) during sleep. Five identical sensor boards were deployed on different positions simultaneously during sleep to detect changes of applied pressure due to heart beating and breathing. One board was set beneath the pillow; the other four boards were set under the mattress aligning with the head, back, hip and calf, respectively. Data were collected from five healthy subjects during a 2-hour's nap individually. Detection performance was evaluated by sensitivity and positive predictivity. The results showed that nearly all of the positions could be used to detect heart rate; both sensitivity and positive predictivity were over 85% among five persons. All of the positions could be used to detect respiration rate except for calf. The highest performance of sensitivity and positive predictivity in respiration rate detection could be found in the hip position, which reached as high as 99%. The optimal position with overall best performance for HR and RR measurement is considered in the hip.