Table 1. Range of sleep times and other relevant data reported for elephants previously in the literature.

Study	Species	Number and Sex	Setting	Total rest/sleep time (h)	Timing of rest/sleep		Timing of major sleep	Time of awakening	Standing rest/sleep observed?	Recumbent rest/sleep observed?
					Day	Night
Benedict and Lee, 1938 [1]	Asian and African	Not reported	Captive—Circus	Not reported	Yes, rarely and short duration	Yes	00.00–04.30	04.30–05.00	Yes	Yes
Kurt, 1960 [2]	Asian (10) and African (7)	5 males, 12 females	Captive—Circus	5.92 h	No	Yes	23.00–07.00	07.00	Yes	Yes
Khüme, 1963 [3]	African	2 males, 1 female	Captive—Zoo	4.17 h	Not reported	Yes	03.00–05.00	05.00	Yes	Yes
McKay, 1973 [4]	Asian	Both, many animals	Wild–Sri Lanka	Not reported	Yes	Not reported	Not reported	Not reported	Yes	Yes
Wyatt and Eltringham, 1974 [5]	African	6 males, 12 females	Wild—Uganda	3.17–3.36 h	Yes, short duration	Yes	04.00–07.00	07.00	Yes	Yes
Guy, 1976 [6]	African	27 males, 21 females	Wild—Zimbabwe	Not reported	Yes, around 2.4 h	Not reported	Not reported	Not reported	Yes	Not reported
Adams and Berg, 1980 [7]	African	7 females	Captive—Zoo	Not reported	Yes	Not reported	Not reported	Not reported	Not reported	Yes
Tobler, 1992 [8]	Asian	12 females	Captive–zoo and circus	3.10–6.90 h	Not reported	Yes	01.00–04.00	06.00–07.00	Yes	Yes
Brockett et al., 1999 [9]	African	3 females	Captive—Zoo	Not reported	Not reported	Yes	01.00–06.00	06.00	Not reported	Yes
Wilson et al., 2006 [10]	African	3 females	Captive—Zoo	Not reported	Not reported	Yes	22.00–02.00	Not reported	Yes	Yes
Horback et al., 2014 [11]	African	7 males, 8 females	Captive—Zoo	Not reported	Yes	Yes	23.00–04.00	05.00–06.00	Yes	Yes
Holdgate et al., 2016 [12]	Asian (28) and African (44)	72 females	Captive—Zoo	African > 2.1 h. Asian > 3.2 h	Yes	Yes	01:00–05:00	Not reported	Yes	Yes