Spending just one week exposed only to natural light while camping in the Rocky Mountains was enough to sync the circadian clocks of eight people participating in a University of Colorado Boulder study with the timing of sunrise and sunset.
They didn't allow flashlights, or other light sources like cell phones and computers. So, it was only natural light that they were exposed to during the week.
I guess this means we should be going camping more often.


In other related research, blue light seams to be rather important to our body clocks. BTW: There is another type of photo receptor in our bodies that is sensitive to blue light. This sensor is in addition to the rods and cones in the eye. We share this sensor with some of the simplest sea creatures that evolved early in the history of life on earth.
Here's one report of many on a study on blue light's effects. They used it to help reset body clocks in teens and elderly people.
http://www.sciencedaily.com/videos/2006/0201-waking_up_teens.htm
Makes me think that having lighting in classrooms that is intense, and blueish in the morning would help the students. It would have to be at least half the intensity of natural sunlight.Teenagers' morning drowsiness is often caused by out-of-tune body clocks, in a condition known as "delayed sleep phase syndrome." Scientists now say that timing exposure to blue light -- avoiding it during the first two hours of being wake, then getting a good dose of it -- can help restore the sleep cycle, so teens feel sleepy earlier at night and are more awake in the morning.
http://www.sciencedaily.com/releases/20 ... 124420.htm
Where do we keep the teens in the morning? For that matter, where do we keep ourselves? Do you get enough bright light in the morning?"This latest study supplements previous work and supports the general hypothesis that the entire 24-hour pattern of light/dark exposure influences synchronization of the body's circadian clock with the solar day and thus influences teenagers' sleep/wake cycles," explains Figueiro. "As a general rule, teenagers should increase morning daylight exposure year round and decrease evening daylight exposure in the spring to help ensure they will get sufficient sleep before going to school."