By the Editors of EQUUS magazine

In the February 2007 issue of EQUUS magazine, California veterinarian Joe Bertone, DVM, describes an equine sleep disorder he has been studying for more than a decade. It occurs when horses, for physical or psychological reasons, are unable to lie down for adequate deep (REM) sleep. After prolonged periods of sleep deprivation, the horse begins to slip into REM sleep at any quiet moment, literally starting to collapse before awakening and catching himself before hitting the ground. This condition, says Bertone, is different than narcolepsy, a neurologic disorder in which otherwise well-rested horses slip into REM sleep during periods of excitement.

The following videos show two sleep-deprived horses having classic "sleep attacks." In both cases, says Bertone, a lack of a herdmate left the horses too insecure to lie down long enough for REM sleep. These videos, along with the story in EQUUS Magazine, provide a fascinating insight into this unusual condition. You can discuss the story with fellow readers in the EQUUS forum.

12-year-old Quarter Horse, whose owner is still searching for a herdmate:

18-year-old Quarter Horse, whose attacks ended when a herdmate was added: