Fig. 6.
The combined use of light (exposure or avoidance), exogenous melatonin ingestion and administration of short-acting hypnotics to facilitate adaptation to phase shifts from the day of arrival. a Depicts westward travel with the first row illustrating normal home time. The next three rows illustrate travel crossing 4, 8 and 12 h time zones, respectively. Each row represents the current phase of the circadian system on the day of arrival. The CBTmin shifts by 0.5 days per time zone crossed, i.e. delays by 2 h per day and application of interventions need to be adapted according to the shifting of the CBTmin. b Depicts eastward travel with the first row illustrating normal home time. The next three rows illustrate travel crossing 4, 8 and 12 h time zones, respectively. Each row represents the current phase of the circadian system on the day of arrival. The CBTmin shifts by 1 day per time zone crossed, i.e. advances by 1 h per day and application of interventions need to be adapted according to the shifting of the CBTmin. We constructed a recommendation based on a scientific measurement (CBTmin and DLMO) that can be reasonably applied for any number of time zones crossed. Travelling > 8 h EAST, it may be preferable to adapt by delay (moving backward) instead of advance (moving forward) as the body clock adjusts to large delays more easily than to large advances). Once CBTmin at the destination occurs within the scheduled sleep period, partial adaptation is achieved, and the individual is likely to encounter less sleep disruption. Once CBTmin at the destination occurs at the same time as pre-travel (home time), complete adaptation is achieved