all Steven Lockley stories

Researchers discover second light-sensing system in human eye

404132862 — Thu, 13 Dec 2007 12:51:32 -0500

New research on blind subjects has bolstered evidence that the human eye has two separate light-sensing systems — one that perceives the familiar visual signals that allow us to see and a second, separate system that tells our body when it is day or night.

Researchers have long known that the eye performed both functions but until recent years it had been thought that both vision and the management of the circadian rhythm that tells us when to be sleepy and when to be alert had been done all at once through the retina’s rods and cones that enable us to see.

When the blues keep you awake

50443248 — Thu, 19 Jul 2007 12:50:17 -0400

Your eyes do more than see.
Researchers at Harvard Medical School demonstrated this by showing that your eyes are part of a light reception system that can keep you alert when sleep starts to fog your brain. When the researchers exposed people to blue light at night, this system immediately increased their alertness and performance on tests.

Blue light special

70652986 — Mon, 26 Mar 2007 05:31:40 -0400

Jet-setters and shift workers now sit in front of glaring white lights to readjust their body rhythms and avoid sleep and alertness problems. New experiments condcuted by Harvard University researchers suggest that they would be better off sitting in front of blue lights. The research also contradicts what many scientists believed for years, that the 24-hour biological clock is set by sight alone. Until 1995, dogma held that the intensity of light striking receptors that give humans color vision also adjust the daily cycle that controls sleep, performance, and other physical and behavioral factors. Now, there is conclusive evidence for a second system that dominates the setting of daily rhythms in creatures from bacteria to international travelers, even blind ones. "The visual system in humans is most sensitive to green light," notes Steven Lockley of Brigham and Women's Hospital, a Harvard research and teaching affiliate. "But when we exposed 12 healthy young men and women to the same amount of either green or blue light, their 24-hour rhythms shifted twice as much with blue than with green."