Fig. 3.

Changes in Profile of Mood States (POMS) agreeable–hostile mood scores dependent on light condition (bright v. dim) and ingestion of a control balanced (BAL) or acute phenylalanine/tyrosine depletion (APTD) amino acid mixture. Values are shown as mean Δ score from evening baseline and standard error of the mean (SEM). A negative change in scores represents a lowering in mood. Significant results are between BAL and APTD within the dim light condition. No significant differences between amino acid mixtures were found within the bright light condition. ^*p < 0.05, ^†p < 0.01. The dim light group had significantly lower ratings of agreeableness on the APTD test session than on the BAL session at 5 hours and 6 hours postingestion. The inset graph depicts the same data represented as a double Δ, with difference scores calculated from morning baseline and net difference scores calculated between APTD and BAL at each time point within each light condition. The significant time points for the agreeable–hostile subscale remained consistent across both analyses. NMI = negative mood induction.