Figure 1

(a). Graph displaying measured 5-HIAA data points per sampling month and 5-HIAA seasonality values (N=479). Measured 5-HIAA concentrations (nmol l⁻¹) per subject are plotted against sampling month. Positively seasonal values are green and negatively seasonal values red. The covariates age and sex are included in the model, explaining why some values in January–June are green when under and red when above the cosine curve (and vice versa for July–December). Red line represents the cosine; black line the LOESS; dashed line the 95% confidence intervals (CIs) of the cosine; and whiskers 95% CIs of median CSF 5-HIAA concentrations per sample month. (b) Median CSF 5-HAA concentrations (in nmol l⁻¹) are plotted against month of CSF sampling (N=479). Bold line represents cosine, thin line represents LOESS and dashed lines represent 95% CIs of the cosine. Whiskers indicate 95% CIs of median CSF 5-HIAA concentrations.