Why do mammals sleep
























Fig. 7.4: Development history of living things shown as a family tree. (50k JPG file)
Fig.7.5: Sea hare. The sea hare, which belongs to the molluscs, also shows a sleeping behavior. (7k JPG file)
Fig. 7.6: Rest-activity rhythms of rats, humans and flies. The rest-activity rhythms are similar. Periods of activity are represented by horizontal lines, periods of rest by white spaces. The rat is active at night, humans and flies are active during the day. (Recording of the fly based on a work by Aschoff and Saint Paul, 1978.) (21k JPG file)
Fig.7.7: Diurnal rhythm of plants (bean). Plants also have diurnal rhythms. Leaf movements of a bean for 3 days. High values ​​of the curve: drooping leaves; low values: spread leaves. Black bars above the curve indicate the dark period. (After Bünning, 1973, Fig. 4, 5.) (22k ​​JPG file)






Fig. 7.8: Sleep deprivation in a rat. Sleep deprivation in rats promotes non-REM sleep with slow EEG waves (= delta sleep) and increases the frequency and duration of REM sleep episodes. The figure shows the spectral curves of the slow EEG waves (1-4 Hz = delta waves) before and after sleep deprivation (duration: 24 hours). Underneath, the REM sleep episodes are shown as rectangles that lie in the "valleys" of the spectral curves. (33k JPG file)