National Geographic : 2018 Aug
Resting in his bunk on the U.S.S. Paul Ham- ilton, a sailor wears light-emitting goggles for a short time after waking. Nita Shattuck of the Naval Postgradu- ate School in Monterey, California, is testing the devices to see if they can reset sailors’ internal clocks, synchronizing them with work shifts rather than the sun cycle. NEXT PHOTO What makes us sleepy? This airtight cham- ber at the Tsukuba sleep institute allows researchers to pre- cisely track a sleeper’s oxygen consumption and thus his metabolic rate—and to measure how it’s influenced, for example, by the brightness and color of ambient light. Find- ing the conditions that best trigger sleep could be the first step in curing insomnia. Sleep reinforces memory so powerfully that it might be best if exhausted soldiers returning from harrowing missions did not go directly to bed.