The Discrete Fourier Transform of the 24-h CSF [Na+] from six participants, combined and derived as described in the Methods. The average PSD is plotted against both the frequency (cycles/min) and the period (h), together with standard error bars. The averaged data reveal the common significant peaks in solid circles (determined by permutation statistics with FDR adjustment as described in Methods): 24.0 h (p < 0.001), 12.0 h (p = 0.002), 1.7 h (p = 0.012), and 1.6 h (p = 0.010).
Harrington et al. Cerebrospinal Fluid Research 2010 7:3 doi:10.1186/1743-8454-7-3