Figure 4: Frigatebirds sleep more and deeper on land than in flight. | Nature Communications

Figure 4: Frigatebirds sleep more and deeper on land than in flight.

From: Evidence that birds sleep in mid-flight

Figure 4

(a) Time spent awake and in SWS and REM sleep in flight and on land. (b) Electroencephalogram (EEG) slow wave activity (SWA; 0.75–4.5 Hz power) while awake and in SWS and REM sleep in flight and on land (median and quartiles for the median). For SWS, SWA is shown for, (1) bihemispheric SWS (BSWS), (2) asymmetric SWS (ASWS) for the hemisphere with greater SWA (ASWS+) and (3) ASWS for the hemisphere with lower SWA (ASWS–). (c) Decline in SWS-related SWA during the first 12 h since landing (top) and the corresponding sleep staging (bottom) in one bird; awake (green), SWS (blue), and REM sleep (red). In the photoperiod bar (middle) grey reflects night.

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