Glasses Can Help Trick Circadian System

OCTOBER 01, 2005

Donning orange glasses to block daylight may be the answer for teenagers who have trouble getting up for school in the morning and falling asleep at night. Researchers said that the sleep problems may be due to a conflict between the teens' internal clocks and the normal 24-hour solar day.

Mariana Figueiro, PhD, of the Rensselaer Polytechnic Institute's Lighting Research Center, explained that individuals need to reset their internal clocks to synchronize them to the light and dark cycles of the solar day. This resetting happens when individuals sleep until their bodies wake naturally, about 90 minutes after reaching their core body temperature, and then expose themselves to daylight. One problem, however, is that some teens may not achieve their normal minimum core temperature until 9 AM, when they are already at school, without the chance for exposure to daylight.

Therefore, when teens are awakened by an alarm clock and leave for school before reaching their core temperature, their circadian system is out of sync and may interfere with the body's normal adjustment of the internal clock. Dr. Figueiro suggested that teens' melatonin levels may be the reason why they do not reach their core temperature until late morning. Some teens' melatonin levels at 1 AM are similar to melatonin levels usually experienced during daylight hours, observed Dr. Figueiro. She and her colleagues proposed that teens wear orange glasses to block daylight when they leave for school. It will keep their circadian system in darkness until their bodies catch up.