A new app to "Entrain" your body clock to minimize jet lag

Two researchers at the University of Michigan have released a new app called Entrain that will help users resynchronize their circadian rhythm to a new time zone to avoid the symptoms of jet lag.

With people traveling long distances across time zones more than ever, jet lag is an increasing problem (Wikipedia): "Jet lag, medically referred to as desynchronosis, is a physiological condition which results from alterations to the body's circadian rhythms resulting from rapid long-distance transmeridian (east–west or west–east) travel on high-speed aircraft. [...] When traveling across a number of time zones, the body clock (circadian rhythm) will be out of synchronization with the destination time, as it experiences daylight and darkness contrary to the rhythms to which it has grown accustomed. The body's natural pattern is upset, as the rhythms that dictate times for eating, sleeping, hormone regulation and body temperature variations no longer correspond to the environment nor to each other in some cases."

There are many "treatments" to alleviate the symptoms of jet lag. All share the goal of resynchronizing your circadian rhythm as quickly as possible. One of the most popular remedies is melatonin but the jury is still out on its effectiveness.

Another popular remedy is "Natural Light Therapy". Your body clock is known to be sensitive to light and so exposure to light is a good way of changing its rhythm. For example, bright light early in the morning will advance your clock (setting it earlier or moving "eastward", i.e. waking up earlier than usual). Bright light late at night will slow down your clock (setting it later or moving "westward", i.e. you need to stay up longer).

The Entrain app devises an optimal schedule of bright and dim light to shift your circadian rhythm to the new time zone as quickly as possible:

“Start by entering your typical hours of light and darkness in your current time zone, then choose the time zone you’re traveling to and when, as well as the brightest light you expect to spend the most time in during your trip (indoor or outdoor.) The app offers a specialized plan and predicts how long it will take you to adjust.”

It is up to the user to use natural or artificial lighting (or shielding from lighting) to meet the schedule.

It is important to note that the efficacy of this app is still theoretical; there are no experimental data yet that shows it will work. Indeed, one cool option is for users to submit their data to the app developers (Figure 1). In this way the developers can evaluate the app's effectiveness and make changes to the scheduling algorithm based on user data.

Technical information on the theoretical rationale of the light schedules is available in the published paper. A YouTube video describes the app itself, which is only available on iOS at this time.

Figure 1. The Entrain app attempts to reset your circadian rhythm through a schedule of light exposure.