You climb into bed worn out and exhausted. But the minute the lights go out, you’re wide awake, worrying. The clock ticks ahead. Your anxiety builds. You wonder how you’ll survive the next day.

For millions of insomniacs, it’s a familiar scenario. According to the National Center for Sleep Disorders Research at the National Institutes of Health, approximately one-third of adults say they have some symptoms of insomnia within a given year, while 10 percent to 15 percent of adults say they have chronic insomnia.

QUIZ: Are You Getting a Good Night’s Sleep?

Insomnia, as you may know all too well, is the inability to fall asleep or stay asleep. It may be acute, lasting just a few nights, or chronic, going on for longer than a month.

Certain people may be vulnerable to insomnia. “There’s growing evidence that sleep ability has a genetic component,” says Mark Mahowald, MD, a professor of neurology and director of the Minnesota Regional Sleep Disorders Center in Hennepin County Medical Center, in Minneapolis. “Some people are super sleepers, while others are fragile sleepers. It’s the fragile sleepers who tend to have insomnia.”

Wow Fact

Average direct (doctor visits, medical treatments) and indirect costs (absenteeism from work) for adults under the age of 64 who have insomnia are about $1,253 more than peers without insomnia.

Insomnia is sometimes linked to an illness, such as depression, substance abuse, multiple sclerosis and GERD. In otherwise healthy people, it can develop after a stressful event, like a death, divorce or job loss, says Donna Arand, PhD, clinical director of the Kettering Sleep Disorders Center, in Kettering, Ohio.

“Insomnia should disappear after the stress has passed,” she says. “However, when people develop bad sleep habits during this acute period of insomnia, these habits can perpetuate the insomnia so that it lasts long after the stress has passed.”

Getting a handle on insomnia can be difficult. Fortunately, adopting the right mind-set and adjusting your habits and routines can go a long way toward lessening — and even eliminating — your insomnia.