Figure 2.

Daily rhythms in plasma concentration of methionine. Rhythms were measured in 6 subjects who slept from 23:00 to 07:00 (Night sleep) or from 0720 to 1500 (Day sleep). Blood was withdrawn every hour starting at 19:00 until 19:00 the next day. Individual data points were transformed to Z scores before averaging across subjects. For clarity purposes standard errors of data points are not presented. Magnitude of standard errors was approximatly 10% of mean values. Note the large pulses in methionine concentrations that appeared in synchrony with the times of feeding.