The U.S. Food and Drug Administration (FDA) has announced that they are requiring a new black box warning on three drugs commonly prescribed to treat insomnia and sold under various brand names. The warning has been added after serious, deadly side effects were reported from individuals sleepwalking, or performing other tasks while sleeping or otherwise not fully awake.

The black box warning, which is the strictest label used by the FDA to indicate potentially life-threatening side effects, will be required for the drugs eszopiclone (Lunesta), zaleplon (Sonata), and zolpidem (Ambien, Ambien CR, Edluar, Intermezzo, and Zolpimist).

The FDA’s decision came after its recent review of 66 cases reported to the FDA Adverse Event Reporting System, or found in medical literature, which documented instances of patients who engaged in activities while they were not fully awake – resulting in serious injuries or death.

In total, 46 reports detailed non-fatal serious injuries, including accidental overdoses, falls, burns, near-drownings, exposure to extreme cold temperatures leading to loss of limb or near death, self-injuries such as gunshot wounds, and apparent suicide attempts. The 20 deaths reported were from carbon monoxide poisoning, drowning, fatal falls, hypothermia, fatal motor vehicle collisions, and apparent suicide.

In addition to the black box warning, the FDA indicated that anyone who is currently using these drugs and has experienced these symptoms should stop or avoid using the drugs.

This is the latest move by the FDA to monitor the use of these sleep drugs. In 2007, it added a similar but less prominent warning, and in 2013, the agency required drug manufacturers to lower the recommended dose for men and women.