In this paper, we present a novel pulseoximetric sensor which can be worn in the ear channel. In previous work, we could demonstrate that measurement of heart rate (HR), arterial oxygen saturation (SpO2) and respiratory related information can be performed with reliable accuracy. Since these results were obtained under laboratory conditions, we now studied the feasibility of a clinical appliance of the sensor system for cardiovascular monitoring during sleep which may allow diagnosis of sleep apnea in future. Therefore, we performed human trials in a sleep laboratory with patients with a clinical suspicion of sleep apnea. The evaluation focus on heart rate and oxygen saturation. Results was compared with standard polysomnography (PSG) measurements and demonstrate that nocturnal long-term measurement of oxygen saturation and heart rate is possible with sufficient accuracy.