We may not know what dreams mean, but frequent nightmares might indicate that you're suffering from a specific mental illness


As much as you want to forget a bad dream as soon as you wake up, don't brush it off so quickly: Frequent nightmares are common in people with early symptoms of depression, reports a new study in the journal Sleep.

Of almost 14,000 adults, 45 percent reported occasional nightmares in the past 30 days. So does that mean they're all at risk for depression? No. Finnish researchers found that the strongest independent risk factors for nightmares were insomnia, exhaustion, and the depressive symptom of "negative attitude toward self." But the mood disorder was the strongest of the three connections, the study authors admit. (Although being scared isn't always bad! Why Being Scared Is a Good Thing.)

In fact, researchers found that 28 percent of people with severe depressive symptoms had frequent nightmares. And women were slightly more likely to have nightmares than men-interesting, considering the fairer sex is about twice as likely to suffer from depression.

While the study authors aren't sure why this connection exists, previous research has found that abnormal sleeping patterns and depression are closely linked as well. A British study found that insomnia and hypersomnia (excessive tiredness) are present in roughly 40 percent of young depressed adults, especially females. And a study last year from the American Academy of Sleep Medicine found that people who sleep shorter or longer than the recommended eight hours have an increased genetic risk for depression. The British researchers speculate that the link stems from sleep's regulation of certain mood-balancing neurotransmitters. (Bad dreams and missed sleep are also two of of 8 Surprising Symptoms of Stress.)

So while it could be perfectly innocent (find out What's Behind Your Weirdest Dreams), if you wake up from scares often-especially if you also have trouble sleeping or waking up-consider talking to your doctor about a possible mood connection.