Posted by: Hourglass PJ16 APR 2014
Many of us may travel long distances across several time zones or do shift work and yet we have to be awake and alert while our bodies’ internal timekeeping (circadian) system is misaligned with the time in the outside world. So-called jet lag leads to poor quality sleep and reduced mental sharpness, often for several days, delaying the time when we again feel ourselves.
Light is the strongest signal to the human circadian system and can slow or speed up the circadian clock, depending on when we are exposed to it. Properly timed exposure to light is, therefore, important for readjusting our internal clock.
Researchers from the University of Michigan have made use of mathematical models to determine the most effective light exposure schedules for retraining the internal clock in the minimum time. By calculating thousands of schedules for different scenarios, using a branch of mathematics called optical control theory, they found that the human internal clock is capable of being shifted more quickly than has been thought.
Practically, these findings mean altering the timing for the start and end of the day, alternating between complete darkness and full daylight, which can be simulated as required.
So, if you have travelled 12 hours from your original time zone and you want to start your day at 7am local time, this model says you must stay in the dark until 1.10pm on your first day and then in the light until 9.50pm. The schedule then shifts each day until you are synchronised to your new time zone, which should happen by the fourth day.
And if you want to give this a try and get some help with the number-crunching, rather than struggle through jet lag in the usual way, there is, perhaps inevitably, an iPhone app to help. It is called Entrain (available at entrain.math.lsa.umich.edu).