Fig. 4. Transitions between behavioral states throughout the day. (A) An example of a forager. (B) An example of a callow with apparent around-the-clock activity. (C) An example of a callow with apparent circadian rhythm in activity. The three bees are from colony H3. Note that the two callow bees manifested all three sleep stages. A, active; IA/G, immobile–active or grooming; FS, first sleep stage; SS, second sleep stage; TS, third sleep stage. For details on behavioral states see Fig. 1 and Table 1. Gray background indicates sleep stages; white background indicates awake states. The horizontal bars at the bottom of the plots depict the subjective time: black bars, subjective night; hatched bars, subjective day. (D) Sleep bout duration (mean ± s.e.m.). Bout duration differed between foragers and callows (two-way ANOVA, age effect, P=0.04) (E) Number of sleep bouts per day (mean ± s.e.m.). The number of sleep bouts differed between foragers and callows (two-way ANOVA, P=0.016). Numbers within boxes indicate the sample size (pooled from the three colonies). Filled bars, foragers; open bars, callows. Asterisks indicate a statistically significant difference between foragers and callows.