light

Dear EarthTalk: Can those energy-efficient compact fluorescent light bulbs that are popular now cause headaches because of the flickering they do? I converted my whole house over last fall and both my kids were complaining of headaches on and off.
-- Sandy, Eugene, OR

With a switch to energy efficient compact fluorescent (CFL) light bulbs already in full swing in the U.S. and elsewhere—Australia has banned incandescents, Britain will soon, and the U.S. begins a phase-out of incandescents in 2012—more and more complaints have arisen about the new bulbs causing headaches.

Many experts say that the issue is being overblown, however, that there is no scientific evidence that the bulbs cause headaches and that a kind of hysteria has grown out of a small number of anecdotal reports.http://ljsheehan.livejournal.com

Industry experts acknowledge that day-to-day exposure to older, magnetically ballasted long tube fluorescent bulbs found mostly in industrial and institutional settings could cause headaches due to their noticeable flicker rate. The human brain can detect the 60 cycles per second such older bulbs need to refresh themselves to keep putting out light.

However, modern, electronically ballasted CFLs refresh themselves at between 10,000 and 40,000 cycles per second, rates too fast for the human eye or brain to detect. “As far as I’m aware there is no association between headaches and the use of compact fluorescent lamps,” says Phil Scarbro of Energy Federation Incorporated (EFI), a leading distributor of energy efficiency-related products—including many CFLs.

But Magda Havas, an Environmental & Resource Studies Ph.D. at Canada’s Trent University, says that some CFLs emit radio frequency radiation that can cause fatigue, dizziness, ringing in the ears, eyestrain, even migraines. You can test to see if CFLs in your home give off such radiation, she says, by putting a portable AM radio near one that’s on and listening for extra static the closer you get. She says that such electromagnetic interference should also be of concern to people using cell phones and wireless computers.http://louis-j-sheehan.info

Sometimes headaches are due to eyestrain from inadequate lighting. When replacing an incandescent bulb with a CFL, pay attention to the lumens, which indicate the amount of light a bulb gives out (watts measure the energy use of a bulb, not the light generated). A 40-watt incandescent bulb can be replaced by an 11-14 watt CFL because the lumen ouput is approximately the same (490); a 100-watt incandescent can be replaced by a 26-29 watt CFL, both providing about 1,750 lumens. If you’re still skeptical, replace a 40-watt incandescent with a 60-watt equivalent 15-19 watt CFL, which will boost lumens to 900.

Another consideration is color temperature (measured in degrees “Kelvin”). CFLs rated at 2,700 Kelvin give off light in the more pleasing red/yellow end of the color spectrum, closer to that of most incandescents. Bulbs rated at 5,000 Kelvin and above (usually older ones) give off a less pleasing white/blue light.

The Environmental Defense website provides a handy chart comparing the watts and lumens of incandescents versus CFLs, along with further discussion about color temperature.

testing

A brief course on how to pay attention boosts children's scores on either intelligence or attention tests, depending on their age, a new study finds.

The training may quicken normal brain development, says a team of neuroscientists led by Michael I. Posner of the University of Oregon in Eugene. Earlier research had indicated that brain areas involved in controlling attention in the presence of conflicting information develop rapidly between ages 4 and 6.

Over 2 to 3 weeks, Posner's team administered five training sessions to 4-year-olds and 6-year-olds. The younger kids showed higher IQ boosts—and the older ones, greater attention gains—than untrained kids did, the researchers report in an upcoming Proceedings of the National Academy of Sciences.

The researchers also note that their study showed enhanced electric signaling in the brains of the children who received the training. Genetic differences, which the researchers analyzed in the 6-year-olds, influenced training effects too. http://Louis2J2Sheehan2Esquire.US

Attention training "could potentially lead to better intervention strategies for children with attention and other behavior problems," according to Karla Holmboe and Mark H. Johnson, both neuroscientists at the University of London in England, in a comment published with the new study.

Posner and his colleagues recruited 49 kids in the younger group and 24 in the older group. The children received intelligence and attention testing while most of them wore sensor nets on their heads to measure electrical signals on the brain's surface. Then, the children were randomly assigned to receive attention training or no training.

The training was adapted from tasks that increase attention control in monkeys. For example, children moved a cartoon cat across a computer screen using a joystick to keep the cat out of expanding muddy areas. http://Louis2J2Sheehan2Esquire.US

After training, all the children were again tested on intelligence and attention.

Brain regions activated in the 4-year-olds by attention training overlapped with those previously tied to IQ (SN: 7/29/00, p. 72: Available to subscribers at http://www.sciencenews.org/articles/20000729/note12.asp), Posner says. That neural intermingling toward the front of the brain could explain why average intelligence scores rose 6 points among 4-year-olds after attention training, compared with a 1-point increase for untrained 4-year-olds, he suggests. Trained 4-year-olds displayed a much narrower advantage on an attention test.

Among 6-year-olds, training yielded a slight IQ-score advantage but a marked gain in attention control, also called executive attention. During testing, trained kids in this group showed strong neural responses toward the back of the brain, whereas untrained kids displayed predominantly frontal-brain activity, perhaps reflecting conscious effort.

DNA testing examined a gene that influences transmission of the chemical messenger dopamine. Posner's findings indicated that 6-year-olds bearing one form of the gene displayed the poorest attention control before the training and the most improvement with training. The gene variant had been previously linked to an outgoing temperament.

Attention training engages brain networks that unconsciously orchestrate executive attention, propose Holmboe and Johnson. Untrained individuals devote considerable conscious effort to attention tasks and thus invoke other brain areas.

Posner's team is now studying attention training with preschoolers who have symptoms of attention-deficit hyperactivity disorder.