National Geographic

Resting in his bunk onthe U.S.S. Paul Ham-ilton, a sailor wearslight-emitting gogglesfor a short time afterwaking. Nita Shattuckof the Naval Postgradu-ate School in Monterey,California, is testingthe devices to see ifthey can reset sailors’internal clocks,synchronizing themwith work shifts ratherthan the sun cycle.NEXT PHOTOWhat makes us sleepy?This airtight cham-ber at the Tsukubasleep institute allowsresearchers to pre-cisely track a sleeper’soxygen consumptionand thus his metabolicrate—and to measurehow it’s influenced,for example, by thebrightness and colorof ambient light. Find-ing the conditionsthat best trigger sleepcould be the first stepin curing insomnia.Sleep reinforcesmemory sopowerfullythat it mightbe best ifexhaustedsoldiersreturning fromharrowingmissions didnot go directlyto bed.