We conducted an open parallel comparison study between Groups to evaluate the possible influence on mental and physical conditions of using a mattress and pillow in which a gel was embedded for 4 weeks. The study subjects consisted of 41 Japanese healthy adult volunteers with high total scores (7 or more) of Pittsburgh Sleep Quality Index and of both sexes aged between 35 to 57 (42.8±5.5) years old. They were divided into 2 groups; the Control Group consisting of 21 subjects and the Study Group consisting of 20 subjects. In the Study Group, DHEA-s (-9.8%) and the creatinine-corrected urinary 8-OHdG (-16.7%) was significantly decreased, and cortisol (27.7%) significantly increased. Of the physical symptoms, “Blurry eyes”, “Lethargy”, and “Coughing and sputum” significantly improved in the Study Group compared with control. Of the mental conditions, “No feeling of happiness”, “Shallow sleep” and “Difficulty falling asleep” significantly improved in the Study Group. For Lifestyle, only the Study Group was affected. Specifically, the “Frequency of alcohol intake” significantly increased along with the “Sleeping hours” (p<0.05). For the survey which entailed using the Pittsburgh Sleep Quality Index, the Study Group showed a significant improvement in “Quality of sleep” (p<0.01). “Sleeping hours” (p<0.05), and “Difficulty staying awake during the day” (p<0.05). Total score decreased from 9.30±2.36 to 6.05±2.80 (p<0.001). These data indicates that the use of a mattress and pillow in which a gel is embedded for four weeks should improve one's quality of sleep and some physical and mental symptoms for healthy adult males and females.