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Circadian clock assessment method in humans
Author(s) -
Doherty Tammy J,
Kolka Margaret A,
Coyne Mary D,
Lindsley Gila,
Stephenson Lou A
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1360-c
Subject(s) - circadian rhythm , chronotherapy (sleep phase) , set (abstract data type) , circadian clock , ultradian rhythm , statistics , computer science , biology , mathematics , endocrinology , programming language
A Circadian Clock Assessment (CCA) method was developed for identifying circadian phase, period (τ), mesor and amplitude using human core temperature (T c ) records showing normal or disrupted circadian T c rhythms (CT c R). CCA uses an algorithm for identifying daily T c nadirs and a series of fit polynomial curves for identifying circadian characteristics. CCA fit irregular T c curve shapes better and produced more accurate estimates of circadian characteristics than Cosinor when applied to artificially generated data. CCA estimates showed less day‐to‐day variability than Cosinor on normal, entrained CT c R data. When CT c R was obviously disrupted, CCA produced estimates of τ that better agreed with visual estimates. CCA failed to identify τ once, in one data set that included both abnormally long (~30 h) and short (~ 12 h) days. Cosinor failed in this case as well. Cosinor had difficulty fitting abnormally long days, occasionally estimated τ in the hundreds of hours, and frequently produced estimates of τ that disagreed, by several hours, with τ estimated using a series of fit cosine curves. In conclusion, CCA is capable of estimating circadian characteristics when CT c R appears normal, as well as when CT c R is obviously disrupted. Applications include individualization of chronotherapy, therapies aimed at clock resynchronization, and basic research studying day‐to‐day changes in circadian characteristics.