I've been reading in bed ever since the book was a Nancy Drew mystery from the school library, illuminated by a flashlight under the covers. I rarely lasted long before conking out.
Now my in-bed library is neatly contained in a Kindle Fire, an elegant computer tablet much brighter than my old flashlight. If the book gets boring, I can catch up on Facebook, check email, watch a video. An hour or more might pass before I make myself shut the thing off.
Even then, I don't always go to sleep right away.
Much as I love it, I'm starting to wonder if I should banish that Kindle from my bedtime ritual. Could it, I wonder, be keeping me up at night?
According to the National Sleep Foundation, more than half of American adults report symptoms of insomnia at least a few nights a week. The biggest gripe is not feeling well-rested in the morning. But a good share of us have trouble getting to sleep — or getting back to sleep.
Loss of sleep is a serious health problem, connected with everything from traffic accidents to cardiac conditions and weight gain. It also can be a warning sign of a health problem such as depression, and it can be the result of many medications. Perfectly healthy people can lose sleep due to stressful events that throw them off so much that insomnia lingers. Shift work is a major hazard to your internal rhythm, especially if you work at night and sleep during the day.
But for some, even slight sleep changes can wreak havoc, and light plays a key role.
"Light affects melatonin production and is one of our clues that goes through the eye and brain, helping us to know when to go to sleep and when it's nighttime,'' explained Dr. Lisa Whims-Squires, a Morton Plant Mease sleep specialist.
Any light can suppress melatonin, a hormone that helps regulate circadian rhythms. But blue wavelength light from computers, phones and compact fluorescent bulbs is thought to be particularly efficient at zapping melatonin.
And no, self-dosing with supplements won't fix the problem, Whims-Squires said.
Dr. Robert Geck, associate program director of sleep medicine at USF Health, said that though many factors can interfere with sleep, "Light probably has the strongest affect on your ability to fall asleep.''
Is TV just as big a problem?
"All light will affect your brain,'' Geck said. "You get the most effect by blue wavelength light, the least by red wavelength light. In a TV, you have the full spectrum. The thought is that the white backlighting (of a tablet, smartphone or laptop computer) would produce more blue tones.''
Which, Geck said, is why his wife has adjusted her device to display white letters on black, meaning less blue light.
I told Geck I planned to try it.
"Probably more important than the backlight is that you're using it in bed,'' he told me. "The best thing would be to leave it out in the living room.
"It's a habit we've gotten into as a society — we do everything in bed. So when you go to bed, your body isn't ready to go to sleep, it's ready to read a book.''
Shutting down the gadgets and dimming the lights is just part of creating a relaxing bedtime ritual that could help if getting to sleep is a problem, he said.
"If you're in the dark, but running around, talking on the phone, that could keep you up too. If you're reading an interesting, stimulating (paper) book, that can be just as bad as reading a boring story that's backlit.''
Insomnia tends to increase with age. But Whims-Squires said she's also seeing younger people with sleep issues that may be related to electronics.
"The 20-somethings always have technology on them,'' she said. And it's all too easy for a quick check of Twitter or Facebook to turn into a marathon cat-and-dog video session.
"High school kids are a whole other beast,'' Whims-Squires said. "It's not necessarily all a light issue, though. It's friends texting them late at night, then they have to be up early for school.''
At any age, it's tough to change habits. Both doctors advise making gradual adjustments to see what works for you.
"What we generally talk about with our patients is trying to limit bright light around bedtime,'' Geck said. "You don't need to go completely non-electrical, but about an hour, an hour-and-a-half before bedtime, it's a good idea to keep yourself in dim light.'' Try an incandescent bulb just bright enough to read a paper book — and not in bed.
"But certainly,'' Geck said, "turn off the computer.''
Of course, that advice only holds if you have insomnia. Geck sometimes uses backlit devices near bedtime without a problem. "As a physician, I'm usually sleep deprived so I don't have trouble getting to sleep,'' he said.
Whims-Squires says she has a consistent sleep schedule and rarely has trouble falling asleep. But that isn't the reason she avoids late-night computer use.
"I'm on it all day with (electronic medical records). Why would I want it on in the evening?''
After talking with Geck and Whims-Squires, I've switched my Kindle to the black background, and am trying not to read in bed. What may help most, though, is respecting my early-to-bed, early-to-rise internal clock, much as I might wish to be night owl.
"The biggest thing is habit,'' Geck said. "We have routines for everything else, and we should utilize them for sleep as well. It needs to be the same thing over and over, so your body understands when it's time to sleep.''