The optimum amount of sleep is not too little but not too much -- at least in middle and old age.
원문출처 : https://www.cnn.com/2022/05/02/health/seven-hours-sleep-optimal-old-age-wellness/index.html
원문출처 : https://www.cnn.com/2022/05/02/health/seven-hours-sleep-optimal-old-age-wellness/index.html