Unique physiology, including differential release of the neurotransmitter acetylcholine, has been linked to the phenomenon.[1] USWS offers a number of benefits, including the ability to rest in areas of high predation or during long migratory flights. The behavior remains an important research topic because USWS is possibly the first animal behavior which uses different regions of the brain to simultaneously control sleep and wakefulness.[2] The greatest theoretical importance of USWS is its potential role in elucidating the function of sleep by challenging various current notions. Researchers have looked to animals exhibiting USWS to determine if sleep must be essential; otherwise species exhibiting USWS would have eliminated the behavior altogether through evolution.[3]