A probabilistic model for the ultradian timing of REM sleep in mice
Fig 5
Relationship between wake episodes and NREM sleep during an inter-REM interval.
(A) (Left) Pie chart indicating the percentage of sequential cycles without (|W| = 0) and with wake episodes (|W| > 0). (Right) Box plot comparing |N| for sequential cycles with and without wake episodes (t-test, t = -3.22, p = 0.0012, n|W|>0 = 122, n|W| = 0 = 825 cycles). (B) (Left) Pie chart indicating the percentage of single cycles without and with wake episodes. (Right) Box plot comparing |N| for single cycles with and without wake episodes (Welch’s t-test, t = -28.64, p = 3.97e-163, n|W|>0 = 2259, n|W| = 0 = 1702). (C) Bar plot showing the distribution of the number of wake episodes during the inter-REM interval of single cycles. Note that 99.63% of single cycles had 8 or fewer wake episodes. (D) (Left) Box plot comparing total NREM duration, |N|, for single cycles with increasing values of total wake duration, |W| (Welch’s ANOVA, F(5,1233.21) = 301.99, p = 3.78e-211). The x-tick q0 corresponds to cycles without wake. The remaining cycles with |W| > 0 were subdivided into quintiles, labeled q1—q5, based on the distribution of |W| for single cycles. (Right) Box plot comparing |N| for single cycles based on the number of wake episodes occurring during the inter-REM interval (Welch’s ANOVA, F(5,475.26) = 246.53, p = 1.65e-129). Note that 97.61% of single cycles contained 5 or fewer wake episodes. (E) Progression of θ power, σ power, spindle rate, and MA rate during NREM sleep before and after a wake episode. Only sequences with at least 1 minute of NREM sleep both before and after wake during the inter-REM interval of single cycles were included. The duration of NREM episodes was normalized. ‘Before’ refers to all NREM sleep in between either the previous REM or wake episode and the current wake episode. ‘After’ refers to all NREM sleep in between the current wake episode and either the next wake or REM episode. Shadings, 99% CI. (F) Bar plot showing average drop (or increase) in θ power, σ power, spindle rate, and MA rate over wake episodes with different durations. All wake episodes for single cycles were divided into five quintiles based on the distribution of their durations. A drop or increase in each variable was calculated by subtracting the average value for 1 min of NREM after wake from the average value for 1 min of NREM before wake (θ: Welch’s ANOVA, F(4,899.90) = 10.48, p = 2.65e-08; σ: ANOVA, F(4,1901) = 1.99, p = 0.093; Spindles: ANOVA, F(4,1901) = 6.22, p = 5.70e-05; MAs: Welch’s ANOVA, F(4,895.63) = 9.13, p = 3.08e-07). Error bars, 95% CI from 1,000 bootstrap iterations.