More than the wars in Iraq and Afghanistan and more than mounting health-care costs, the number-one thing that’s keeping Americans up at night is the bad economy. The National Sleep Foundation’s annual Sleep in America poll reported that almost one-third of the participants recently experienced “disturbed” sleep at least a few nights a week because they were concerned about the economy, employment and their personal finances.

“When we go to bed and everything is quiet, that’s when things sneak up on us,” says Rebecca Scott, Ph.D., a sleep specialist at the New York Sleep Institute and assistant research professor at New York University's School of Medicine. “It’s impossible to be anxious and go to sleep at the same time.” Bedtime is often when people talk to their spouses about the events of the day, including looming fears and worries. Instead of winding down and signaling the sleep cycle, the brain fires back up.

If you lose sleep once in a while, it’s called transient insomnia, and it’s usually connected to a specific issue, like financial fears. Besides feeling a little tired the next day, you’ll be okay after the occasional sleepless night. But if restless nights begin to stack up, you may have chronic insomnia and that’s when you start suffering side effects, says Dr. Scott.

NEXT: When insomnia becomes chronic >>