Fig 2. Identification of circadian- and behaviour-influenced metabolites.

(A, B) Examples of metabolites that are influenced by the circadian cycle (A: tryptophan and methionine sulfoxide) and that are influenced by the behavioural cycle (B: hexanoylcarnitine [C6] and alanine). Data are presented as mean ± SEM. Relative clock time reflects the time since the start of the individual habitual rest period during baseline. (C) Phase shift during the night shift condition relative to baseline of the 32 metabolites that are significantly rhythmic at both baseline and during the night shift condition. Symbols represent whether the metabolites were classified as circadian-influenced, behaviour-influenced, or neither. The direction of the arrow represents the average phase shift of the behaviour-influenced metabolites. Length of the arrow represents the mean resultant vector length, a measure of the spread of the circular data. No arrow is shown for the circadian-influenced metabolites, because the phase shift of the metabolites was not nonuniformly distributed (p = 0.16, Rayleigh test). (D) Amplitude of the 32 metabolites that were identified as rhythmic during baseline and the night shift condition. Numerical data underlying the results presented in this figure are available in S2 Data. C6, hexanoylcarnitine.