Insomnia got you down? Avoiding common sleep killers may help

You used to wish you could stay up all night, but now you lie in bed, staring at the clock and thinking only of how tired you'll be in the morning. Or maybe you've always suffered from insomnia.

It's hard to calm your mind as one worry after another — bills, your kids' school problems, the offhand comment your boss made — crowds in and keeps you wound up. This can cause trouble falling asleep, or cause you to wake up in the night.

When you sleep, your body actually is a buzzing hive of activity: Your brain preserves what you've learned that day as memory, your endocrine system produces hormones that stimulate muscle repair and your immune system does a reboot to help protect you from disease.

Recent research has linked sleep deprivation to everything from obesity to diabetes to heart disease to cancer.

It's enough to keep you up at night. In fact, for many of us, worry is the No. 1 cause of insomnia. But there are plenty of other things we may not think about — from the temperature of the room to the venti Frappuccino you chugged during the late-afternoon slump — that also keep us staring at the ceiling.

Here are some common sleep killers, and how to defend yourself against them without resorting to pills.

Too much coffee

Caffeine — found in coffee, of course, as well as tea, colas and even some medications — blocks the sleep-inducing action of the brain chemical adenosine. It also can reduce the amount of the sleep hormone melatonin you make. Not only will it lead to trouble dozing off, but you'll sleep restlessly. In an Israeli study, subjects given caffeinated coffee had about half as much melatonin in their systems as those who were given decaf. They also took twice as long to fall asleep and slumbered an average of 79 minutes less.

Too much light

Although playing a few rounds of Words With Friends on your iPad or spending two hours in front of the tube watching "The X Factor" and "Glee" may help you wind down, your body's response to short-wave blue light emitted by these devices' backlit screens is, "Hey, more daylight! Let's stay up and play." (This is true for compact florescent, LED and incandescent lights, too.)

Sleep hormones kick in at about 9 p.m. or 10 p.m., but if the bedroom never gets dark, your body holds off melatonin production, making it harder for you to fall asleep.

What's better shut-eye worth?

Americans are so sleep-starved that in a recent survey, 67 percent said they'd trade a vacation day and 62 percent their cable service for better nights. It's hard to think of anything else that would get one to sacrifice time off "Homeland." But when you get only seven or six (or even fewer) hours of sleep, you feel lousy the next day. You have the response time of a tortoise and possibly a headache, too, and you can't remember if you need to call the dentist or the vet.