Figure 2.

(a) The per cent time (mean+s.e.m.) spent in wakefulness (green), non-REM sleep (blue) and REM sleep (red) for each hour of the day. (b) The time spent feeding (black) based on the occurrence of mastication artefacts in the EEG/EMG recordings. The values are plotted at the beginning of each hour. Data for the first 24 h following release were omitted. The area shaded in grey shows the time from sunset (18.00) to sunrise (06.20). (c) Actogram showing seven months of activity recorded from a sloth with an automated radio-telemetry system. Each horizontal line is data from one 24 hour period plotted twice. The black lines indicate periods when activity was detected. Note that the two white vertical bands at 6 and 30 h correspond to the clear peak in sleep (a) and absence of feeding (b) occurring at this time. See methods in the electronic supplementary material.