Table 2.

Spindle density only correlated with sigma-power when data were analyzed in time bins of 15 minutes duration or shorter

Bin width	1 minute	15 minutes	30 minutes	4 hours
Pearson’s correlation coefficient (r)	0.21	0.60	0.57	−0.57
p-value	3.13 × 10−5	0.01	0.14	0.43

Pearson’s correlation coefficient and p-values were given for comparisons of spindle density and sigma-power in 15-minute bins and 30-minute bins. Both cases reflect the full 4-hour period used throughout the rest of the study.