Tuesday, September 25, 2012

Light from Tablet Computers May Delay Sleep, Especially in Teens

I admit I love my gadgets – especially my laptop and e-reader, I’m also, as a doctor, aware of the effects that the artificial light from these devices can have on our sleep, especially following prolonged and late-night use.

The artificial, short-wave light from TV and computer screens can suppress melatonin production and throw off circadian rhythm, preventing deep, restorative sleep. Prolonged sleep disruption may also lead to increased risk for diabetes and obesity.  A new study  released in late August reinforces my opinion with some data.

Researchers at the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute in Troy, NY tested the effects of self-luminous tablets on melatonin suppression. Melatonin is a hormone produced by the pineal gland at night and is involved in regulating our sleeping and waking cycles.

The study was funded by Sharp Laboratories of America and led by Mariana Figueiro, associate professor at Rensselaer and director of the LRC’s Light and Health Program. Co-authors of the study are LRC director and professor Mark S. Rea, LRC research specialist Brittany Wood, and LRC research nurse Barbara Plitnick.

For the study, 13 participants used self-luminous tablets to read, play games and watch movies. The participants were divided into three groups. The first group viewed their tablets through a pair of clear goggles fitted with blue light. This was the “true positive” group because blue lights are known to be a strong stimulus for suppressing melatonin.

The second “control” group viewed their tablets through orange-tinted glasses, which filtered out the short-wavelength radiation that can suppress melatonin. The third group did not wear any glasses or goggles. Each tablet was set to full brightness.

The results of the study were clear: After only two hours of exposure to electronic devices with self-luminous “backlit” displays, the participants’ melatonin levels were suppressed by about 22 percent. According to lead researcher Mariana Figueiro, stimulation of the circadian system to this level may delay sleep in those using the devices prior to bedtime, especially in teens.

The researchers also determined that the type of task being performed on the tablets also determines how much light is delivered to the cornea, and therefore the impact the self-luminous light has on nighttime melatonin levels. In other words, the researchers pointed out that it is important to measure how much light a person receives from the self-luminous device.

So, what can be done with this new information? How can we use it to improve our sleep and general health? One, we can all become more aware of how much time we—and our children—spend staring at our tablets, computer and TV screens late at night. As adults, it is up to us to monitor ourselves and our children, and have the discipline to turn these machines off at least an hour before bedtime.

LRC research specialist Brittany Wood said, “Technology developments have led to bigger and brighter televisions, computer screens, and cell phones. To produce white light, these electronic devices must emit light at short wavelengths, which makes them potential sources for suppressing or delaying the onset of melatonin in the evening, reducing sleep duration and disrupting sleep. This is particularly worrisome in populations such as young adults and adolescents, who already tend to be night owls.”

Although pre-teens and teens love their late-night electronics, as parents, it is our responsibility to monitor our children’s computer use, or at the very least in older teens, educate them and make them aware of the potential; side effects of prolonged use.

Researcher Figueiro also feels that tablet display manufacturers can use this information to determine how their products affect circadian system regulation, and as a result, design more “circadian-friendly” electronic devices that could either increase or decrease circadian stimulation depending on the time of day. For example, screens that reduce circadian stimulation in the evening for a better night’s sleep, and increasing in the morning to encourage alertness.

Figueiro had another interesting idea about tablet light therapy: In the future, manufacturers might be able to use related data to design tablets that minimize symptoms of seasonal affective disorder, and sleep disorders in seniors. People might even be able to receive light treatments while playing games or watching movies, making light therapy much more enjoyable than just sitting in front of a light box.

Until manufacturers develop more “circadian-friendly” electronic devices that increase or decrease light exposure based on time of day, Figueiro offered several recommendations to reduce the effects of self-luminous tablet light on sleep, including dimming these devices at night as much as possible in order to minimize melatonin suppression, and, as I mentioned before, limiting the amount of time spent using these devices prior to bedtime.

Here’s another idea: Why not turn off the devices before bed, and pick up a good old fashioned paper book. You’ll be out like a light before you know it.

Read the full study entitled, “Light From Self-Luminous Tablet Computers Can Affect Evening Melatonin, Delaying Sleep.”

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