Peripatetic school used by earlier philosophers such as Socrates. Aristotle and his colleagues first began to use the Lyceum in this way about 335 BC, after which Aristotle left Plato's Academy and Athens, and then returned to Athens from his travels about a dozen years later. Because of the school's association with the gymnasium, the school also came to be referred to simply as the Lyceum. Some modern scholars argue that the school did not become formally institutionalized until Theophrastus took it over, at which time there was private property associated with the school. Originally at least, the Peripatetic gatherings were probably
Shift work may be due to alterations in circadian rhythm: melatonin, a known tumor suppressor, is generally produced at night and late shifts may disrupt its production. The WHO's International Agency for Research on Cancer listed "shiftwork that involves circadian disruption" as a probable carcinogen. Shift work may also increase the risk of other types of cancer. Shift work also increases the risk of developing cluster headaches, heart attacks, fatigue, stress, sexual dysfunction, depression, dementia, obesity, metabolic disorders, gastrointestinal disorders, musculoskeletal disorders, and reproductive disorders. Shift work also can worsen chronic diseases, including sleep disorders, digestive diseases, heart disease, hypertension, epilepsy, mental