Optimal adjustment of the human circadian clock in the real world
Fig 3
Optimal schedule deployed in real life.
(A) Activity data (black line) from one subject who took three trips (shaded in blue) in 25 days. Optimal schedules (grey for avoiding light, and yellow for receiving light) to adjust to the new time zones were computed for each trip. We can see the subject generally followed the recommended optimal schedule for his/her first and last trip, but not for the second trip. (B) A sample of 147 Entrain users who submitted their motion data during trips shows how the recommended schedules were followed each hour of the day. Each yellow/gray bar represents the average percentage of active time during the scheduled light/dark period at each hour of the day. Unsurprisingly, regardless of the recommended light-receiving/light-avoiding schedule, the activity pattern peaks during the day and drops during the night. (C) This figure shows the extent to which the subjects followed the recommended schedule for different time durations. Each yellow/gray bar represents the average percentage of active time at each recommended duration of the light/dark period. As the recommended period of darkness increases, so does the percentage of active time under recommended darkness. (D) This figure shows how the recommended schedules were followed as subjects traveled across different time zones, where positive time zones represent traveling east. Each yellow/gray bar represents the average percentage of active time during the recommended light/dark period for the total number of time zones crossed. (E) This figure shows the percentage of active time under recommended darkness under the recommended light for the total number of time zones crossed. As can be seen, the optimal schedule is harder to follow when flying west on short trips. The low compliance with the schedule may also occur because people do not feel the need to observe light and dark recommendations for short phase delays.