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Johns Hopkins Health - Lights Out for Sleep

Summer 2010
Issue No. 9

Lights Out for Sleep

Date: July 20, 2010

woman in bed with laptop

The cool-blue glow of our electronics plays a huge role in our sleep cycles. Too often we don't know when-or why-to shut down

It’s 10 p.m. and you’re cross-legged on your bed with your laptop on your knees, maybe your cell phone by your side and perhaps even your television on for company. Sound familiar?

With all of that stimulation, it’s no wonder Americans are getting less sleep over time. But the culprit isn’t the devices on their own; rather, it’s the light they emit that’s helping to disrupt our sleep.

“Part of the problem is exposure to light in the evening,” says sleep specialist David Neubauer, M.D. Possibly more problematic, he adds, is the type of light to which we’re exposed.

The effect of light is strongest in the blue light range. It’s the most potent part of the spectrum, with the capacity to keep us alert and stimulated. It’s also the type of light that shines on through computer monitors, televisions and cell phone screens.

As a culture, we’ve already been staying awake longer for years. Now, with more devices emitting more blue light later at night, we’re creeping into sleeplessness.

 “Unfortunately, most people don’t consider sleep to be in the same category as other health-related issues,” says Nancy Collop, M.D., head of Johns Hopkins’ sleep disorders program. That’s too bad, because lack of adequate sleep adds up.

Short-term consequences affect our memory and cognitive ability and double the risk of an occupational injury. Long term, sleep deprivation can lead to high blood pressure, heart problems, stroke, obesity, depression and other mood disorders.

“We really need to get to a place where our culture values sleep,” Neubauer says.
The first step may be as easy as shutting down the glowing blue screens at bedtime and keeping them out of our bedrooms.

Tune in to Your Body
Two different, but related, mechanisms decide when we sleep:

  • Homeostatic drive—Basically, the longer you go without sleep, the more tired you become until sleep ultimately wins out.
  • Circadian rhythm—Our 24-hour cycle of biochemical, physiological and behavioral processes, which is reinforced by exposure to light and other stimuli.

If sleep problems might be affecting your health, consult a specialist at Johns Hopkins. Call 877-546-1872. For more about sleep disorders, visit