Figure 1
Daily rhythm of tryptophan blood level in the horse. Each time point represents the mean value ± SD. Φ represents the acrophase. Black and white stripes at the bottom of the graphic represent dark and light duration of the natural photoperiod.
Figure 2
Daily rhythm of serotonin blood level in the horse. Each time point represents the mean value ± SD. Φ represents the acrophase. Black and white stripes at the bottom of the graphic represent dark and light duration of the natural photoperiod.