Narrator: This is Science Today. Using sleeping pills to alleviate sleeping problems or anxiety is only supposed to be for short-term use, but studies indicate about two-thirds of the market is going to long-term users. Because of this, Daniel Kripke, a professor of psychiatry at the University of California, San Diego says there should be more research conducted on long-term usage.

Kripke: The effects on the long-term user are almost never studied and physicians would be better guided if they had more information from which to work.

Narrator: Kripke has conducted previous studies that found there's an increased risk of death associated with long-term use of sleeping pills.

Kripke: We found that people who said they were taking sleeping pills every night of the month were more likely to have died after six years than people who didn't take them. And the increased risk of death with taking sleeping pills every night was about the same as the increased risk of smoking one or two packs of cigarettes a day.

Narrator: For Science Today, I'm Larissa Branin.