12 hours and 1.65 hours Hours
||Human Homo sapiens
||Harrington MG et al., Cerebrospinal fluid sodium rhythms. Cerebrospinal Fluid Res. 2010 Jan 20 7: 3. p.4 right column 2nd paragraphPubMed ID20205754
||Sodium and potassium cations were calibrated (and
continuously verified) with NIST-certified standard mixtures
(SPEX CertiPrep, Metuchen, NJ, USA).
||The distribution of sodium varied much more than potassium, and there were statistically significant
rhythms at 12 and 1.65 h periods.