On the link between rapid eye movement sleep and yawning

Excerpt

In a recent review article (The Lancet Neurology, 21(10), pp.937–946), Seigel [1] argues that rapid eye movement (REM) sleep evolved as a thermostatically controlled brain heating mechanism, extending upon a proposal by Wehr [2] 30 years prior. This hypothesis proposes that the heightened and distinctive neurological activity associated with REM sleep functions to warm the brain following decreases in brainstem temperature and reductions in metabolism and energy consumption that occur during non-REM sleep. Accordingly, REM sleep serves to keep the brain metabolically functional and easily awakened. Evidence in support of this hypothesis appears strong and is presented from various studies of comparative thermoregulatory physiology and REM sleep. Notably, Seigel [1] draws attention to the striking inverse relationship (r =  − 0.975) between core temperature and REM sleep duration among birds, placental mammals, marsupials, and monotreme species. …