Fur Seals Suppress REM Sleep for Very Long Periods without Subsequent Rebound (Current Biology)

Lyamin et al. show that although fur seals have 80 min of REM sleep a day on land, they have little or no REM sleep when in water for as long as 2 weeks. When they return to land they show little or no REM rebound. Their switch to from bilateral to unihemispheric nonREM sleep in water may make REM sleep unnecessary.