- The eye has a photoreceptor that picks up certain wavelengths of light, and then sends a signal to the hypothalamus.
- The hypothalamus then secretes a hormone that tells our body to rest.
- A new bio-bulb would help people see at night without messing with their body's natural mechanisms.
As late-night workers and long-distance travelers already know, shifting time zones or work periods throws the body's natural clock out of whack.
Even regular folks often find it nearly impossible to get a restful sleep for several hours after sitting under bright lights after the sun has gone down (some call it the Fenway Park phenomena).
Now a Florida inventor is testing a new LED bio-bulb that could regulate the body's circadian rhythm by helping control the production of melatonin, the body's sleep hormone that tells us when it's nighttime.
This can be done by eliminating a small segment of the blue wavelength of light (around 465 to 485 nanometers) produced by the lightbulb, according to Fred Maxik, founder and chief technology officer of Lighting Science Group Corp., a Satellite Beach, Fla., firm.
"We're looking at a way to filter out that part of the spectrum, and still have a white light," Maxik said. "Our ability to restore the natural position of where we were and natural hormonal secretions is an appealing one."
Nearly 20 years ago, medical researchers discovered that the eye has a separate photoreceptor that picks up wavelengths of light, and then sends a signal to the hypothalamus which secretes melatonin.
While melatonin doesn't make you sleep, it does tell the body to prepare to rest. Some lighting manufacturers have already developed lights designed to keep people awake by boosting those wavelengths and suppressing the body's natural melatonin cycle.
Maxik says he's trying to do the opposite, help people see what they are doing at night -- reading, doing homework or watching TV let's say -- without making it hard to fall asleep when they are ready. He's even trying to make it dimmable.
"You need to remove part of the light spectrum, a significant notch taken out of that, and create a light that people don't see as something that's unusual," Maxik said. "It has to be something that's natural."
Maxik is testing his lighting device in clinical trials being run by Steven Lockley, a neurobiologist at the Harvard Medical School and Brigham and Women's Hospital Sleep Center.
Lockley said that participants won't know whether they're getting a normal light or the blue-less light from the new bio-bulb.
"We're ramping down alertness," Lockley said.
Lockley published paper earlier this year showing that light from overhead fluorescent fixtures can delay melatonin production and sleep by up to 90 minutes.
Some experts say the project faces both engineering and biological challenges. For one, it's difficult making a bulb that eliminates all the individual wavelengths that trigger human photoreceptors, says Mark Rea, professor of cognitive science and director Rensselaer Polytechnic Institute's Lighting Research Center.
"If you get rid of 20 nanometers, you still have absorption of 35 (nm) on each side and you still have sufficient energy to have the biological effect," Rea said. "It's a common misnomer that filtering out the peak reduces the biological sensitivity, it's just not true."
Rea says that to accurately produce the desired effect, researchers have to know the spectrum of the light as well as the amount of energy produced; the duration of the exposure; the spatial distribution of the light -- whether from the periphery of the eye or straight ahead; and finally when the light is being received.
"It's complicated," he said.
Maxik says he's also working with researchers at NASA's life science group to adapt an LED lighting system for astronauts that need to accurately regulate their body clock while being exposed to sunlight and darkness every 90 minutes they orbit Earth.
If the Harvard/Brigham and Women's clinical trials go well, Maxik says he hopes to have the new LED bio-bulb ready within two years.