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Plot of the logarithm of sleep cycle time in minutes, the period between REM and non-REM sleep, versus the logarithm of body size, ln(M), in kilograms. The slope computed by using OLS regression is 0.19 (P < 0.0001; n = 32, 95% CI: 0.14, 0.23). Note that the 95% CI includes the predicted values of 3/16 and 1/6 but excludes 1/4 [Reproduced with permission from ref. 53 (Copyright 2006, Springer).].
