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Optimal Schedules of Light Exposure for Rapidly Correcting Circadian Misalignment

Figure 3

Optimal schedules for re-entrainment to 8 and 12 hour shifts of the LD-cycle.

Predicted core body temperature minima (CBTmin, magenta triangles) are plotted against the pattern of optimal exposure to bright light (200 lux–10,000 lux, yellow), moderate light (100 lux, white), and darkness (0 lux, black). Predicted CBTmin under noisy light levels (See supplemental figure S1), with circadian period randomly sampled from an experimentally measured distribution [18], is plotted for 20 hypothetical subjects (blue circles). The timing of entrained CBTmin in the new time zone is indicated by the dotted line. Circadian amplitude at CBTmin is indicated by the brightness of the markers, with white corresponding to zero amplitude. The subjects are initially entrained to a 16∶8 LD-cycle in moderate light. At day 0 the schedule shift occurs. Optimal schedules are grouped in rows by maximum admissible bright light level (yellow), and in columns by effected phase shift. Figures (A), (B), (C) use a maximum light level of 10,000 lux; (D), (E), (F) use 1000 lux; (G), (H), (I) use 500 lux; (J), (K), (L) use 200 lux; (M), (N), (O) use 100 lux. Figures (A), (D), (G), (J), (M) are optimal schedules for an 8-hour delay; (B), (E), (H), (K), (N) a 12-hour shift; (C), (F), (I), (L), (O) an 8-hour advance.

Figure 3