Changes in diffusion tensor imaging (DTI) indices of white matter microstructure after waking.

<p>(<b>A</b>) The participants underwent magnetic resonance imaging in the morning [7:30AM; time point (TP)1] after a night of normal sleep in their own homes, after a day of waking (TP2), and then after another 9 hours of waking (TP3). (<b>B</b>) Significant increases in fractional anisotropy (FA) after a day of waking (red-yellow color; left panel). (<b>C</b>) Significant decreases in radial diffusivity (RD) after a day of waking (blue colors; left panel). (<b>D</b>) Significant decreases in mean diffusivity (MD) after a day of waking (blue colors; left panel).</p

Clusters with significant changes in DTI indices of white matter microstructure after a day of waking (TP1 compared with TP2).

<p>Clusters with significant changes in DTI indices of white matter microstructure after a day of waking (TP1 compared with TP2).</p

Changes in diffusion tensor imaging (DTI) indices of white matter microstructure after sleep deprivation and associations with sleepiness.

<p>(<b>A</b>) Significant decreases in fractional anisotropy (FA) after sleep deprivation (blue colors; left panel). (<b>B</b>) Significant decreases in axial diffusivity (AD) after sleep deprivation (blue colors; left panel). Averaged DTI values at time point (TP)2 and TP3 across significant voxels are shown for each participant using individual colors in the right panels of (<b>A</b>) and (<b>B</b>). Values from the same participant are connected with a line. (<b>C</b>) No significant relationship was observed between the decrease in FA in the voxels shown in (<b>A</b>) and Stanford Sleepiness Scale (SSS) score at TP3 (<i>R</i> = −0.33, <i>P</i> = 0.14). (<b>D</b>) Because the FA decreases in the significant voxels of (<b>A</b>) were mainly driven by AD reductions, we examined whether reductions in averaged AD within these clusters correlated with SSS score and found a significant negative association (<i>R</i> = −0.63, <i>P</i> = 0.002), indicating greater sleepiness in subjects with larger AD reductions after sleep deprivation. (<b>E</b>) No significant relationship was found between AD reductions across the voxels shown in (<b>B</b>) and SSS score (<i>R</i> = −0.26, <i>P</i> = 0.265). (<b>F,G</b>) Averaged AD across all voxels of the white matter skeleton decreased significantly from TP2 to TP3; this decrease was significantly correlated with sleepiness at TP3 (<i>R</i> = −0.65, <i>P</i> = 0.001). The left side of the brain images represents the right hemisphere.</p

Clusters with significant changes in DTI indices of white matter microstructure after sleep deprivation (TP2 compared with TP3).

<p>Clusters with significant changes in DTI indices of white matter microstructure after sleep deprivation (TP2 compared with TP3).</p

Demographic, sleep, and heart rate variability at baseline.

Demographic, sleep, and heart rate variability at baseline.</p

The impact of sleep deprivation on HRV and HR.

The impact of sleep deprivation on HRV and HR.</p

Main effects and interactions of group and measurement period on heart rate variability, heart rate, and ANT measures.

<p>Line graphs illustrate means and 95% confidence intervals for log-transformed HF-HRV (1A), HR (1B), mean reaction time (1C), Orienting t-values (1D), Alerting t-values (1E), and Conflict t-values (1F). Error bars represent 95% confidence intervals, which are corrected to remove between-subject variability. M1 = Morning 1; N1 = Night 1, M2 = Morning 2.</p

The relationship between orienting and HRV.

<p>Plots demonstrate the relationship between orienting and HRV at baseline (3A) after sleep (3B) and after sleep deprivation (3C). The blue histogram shows the posterior distribution for the correlation <i>p</i> with a 95% highest density interval (HDI). The scatterplots illustrate the relationships between these two variables, with superimposed posterior predictive distributions. The larger light blue ellipse shows the 95% highest density region while with smaller dark blue ellipse shows the 50% highest density region. The histograms on the top x-axes and right y-axes show the marginal distributions of the data. HDI = Highest density interval.</p

The relationship between ANT scores and HRV.

<p>The relationship between ANT scores and HRV.</p

Data collection times.

<p>Data collection times.</p