Brain activity of diving seals reveals short sleep cycles at depth

• Published in: Science (American Association for the Advancement of Science) Vol. 380; no. 6642; pp. 260 - 265
• Main Authors: Kendall-Bar, Jessica M, Williams, Terrie M, Mukherji, Ritika, Lozano, Daniel A, Pitman, Julie K, Holser, Rachel R, Keates, Theresa, Beltran, Roxanne S, Robinson, Patrick W, Crocker, Daniel E, Adachi, Taiki, Lyamin, Oleg I, Vyssotski, Alexei L, Costa, Daniel P
• Format: Journal Article
• Language: English
• Published: United States The American Association for the Advancement of Science 21.04.2023
• Subjects: Animals; Brain - physiology; Diving; Marine mammals; Mirounga angustirostris; Paralysis; Predators; REM sleep; Remote monitoring; Seals; Seals (animals); Seals, Earless - physiology; Sleep; Time Factors
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.adf0566

Sleep is a crucial part of the daily activity patterns of mammals. However, in marine species that spend months or entire lifetimes at sea, the location, timing, and duration of sleep may be constrained. To understand how marine mammals satisfy their daily sleep requirements while at sea, we monitored electroencephalographic activity in wild northern elephant seals ( ) diving in Monterey Bay, California. Brain-wave patterns showed that seals took short (less than 20 minutes) naps while diving (maximum depth 377 meters; 104 sleeping dives). Linking these patterns to accelerometry and the time-depth profiles of 334 free-ranging seals (514,406 sleeping dives) revealed a North Pacific sleepscape in which seals averaged only 2 hours of sleep per day for 7 months, rivaling the record for the least sleep among all mammals, which is currently held by the African elephant (about 2 hours per day).