This study developed a sensory board and investigated the optimal position to monitor heart rate and respiration rate during sleep. The sensory board was devised using a circular piezoelectric cell which is sandwiched between two acrylic boards. Four identical boards were installed in 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 three boards were set under the mattress close to the back, hip and calf level positions. Data were collected from five healthy university students during a 2-hour’s nap individually. At the same time, Lead I ECG and nasal thermistor signals were recorded as heart rate and respiration rate references, respectively. These rates were detected by applying the same algorithm on the data collected from different positions. Detection performance was evaluated by sensitivity and positive predictivity. The results showed that nearly all positions could be used to detect the above two parameters but performance was different slightly in positions. Heart rate could be detected in all positions, and both sensitivity and positive predictivity were over 97% among all five persons. Sensitivity and positive predictivity in respiration rate detection could be found the highest performance in the back position; both performance indexes were over 97% on average and close to the heart rate detection.