For approximately one million years human beings have lived in a physiological rhythm determined by day and night—that is, a rhythm of about 24 hours. So ingrained is this habit that a daily ...

After every afternoon movie she saw, for two years, a teen-age acquaintance of Chicago Physiologist Nathaniel Kleitman took her own temperature. A girl in her 20s took similar readings after 29 shows ...

2023-12-24T16:52:42-05:00https://ximage.c-spanvideo.org ...