Commander

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This undated photo released by the U.S. Navy shows USS Scranton submarine Cmdr. Seth Burton. Scientists at the Naval Submarine Medical Research Laboratory in Groton, Conn., concluded submarine sailors, who traditionally begin a new workday every 18 hours, show less fatigue on a 24-hour schedule. The first submarine to try the new schedule on a full deployment was the Scranton, led by Cmdr. Burton, who said he found that the more consistent sleep pattern made up for any effects from working slightly longer shifts. (AP Photo/U.S. Navy)