The Science of Chronoshift

Introduction to Jet Lag

When travelling across many time zones quickly, you will likely experience jet lag.

Jet lag is a temporary disorder that often causes daytime fatigue and disturbed sleep. More serious symptoms include headaches, indigestion and depression. The severity of the symptoms depends on factors such as distance and direction of travel, age, sleeping habits and genetic disposition.

As you adjust to the new time zone, which occurs naturally, most of your symptoms will disappear.

The Sleep-Wake Cycle

Sleep is essential for survival. Your brain makes you feel sleepy in the evening and keeps you asleep during the night.

To make you sleepy at the right time, the brain has a clock that cycles through every 24 hours; the circadian clock ( circa: ‘around’ and diem: ‘day’). The circadian clock controls the timing of activities such as sleep and wakefulness, and regulates other processes such as digestion and body temperature.

The circadian clock is kept in sync by environmental inputs. The most important environmental input is light. The presence of light in the morning signals day time, and the absence of light in the evening signals night. Your brain conveys this information to the rest of your body.

Exercise, stress and meal times are some other factors that influence the circadian clock.

Jet Lag and the Sleep-Wake Cycle

When travelling across many time zones, the circadian clock becomes confused because its time doesn’t match with the environmental inputs.

For example, imagine you fly from New York to Berlin and your flight lands at 7 AM Berlin time. The circadian clock is still on New York time (1 AM) which is 6 hours behind Berlin time. It prepares you for bed by increasing melatonin production (a sleep-promoting hormone) and reducing body temperature. However, its morning in Berlin and the light reaching your eyes tells the circadian clock that its now morning.

This confusion between the circadian clock and environmental inputs causes jet lag.

How Chronoshift Works

Chronoshift aims to reduce the effects of jet lag by adjusting the circadian clock to your destination time zone in the days preceding the trip.

Chronoshift achieves this by breaking the time zone difference (between the departure and destination cities) and spreading it out over a few days (the number of days you would like to start adjusting beforehand). Chronoshift then generates an optimal sleep-wake schedule to make the transition as smooth as possible.

Example of a Trip Schedule

Imagine you are traveling from London to Toronto in 5 days. You typically sleep from 10 pm to 6 am.

Based on the time difference between London – Toronto, and your trip information, Chronoshift will generate the following schedule (illustrated below).


The grey bars with numbers represent the local times, and blue portions of the schedule indicate ideal sleep times. Each row is a new day. On the first day that you start adjusting, Chronoshift suggests you sleep from 11 pm to 7 am. The following day Chronoshift suggests sleep occur from midnight to 8 am and so on. Ideally, just before departure for Toronto – you should be sleeping around 3 am and waking up around 11 am.

This schedule will align you with Toronto time before leaving London.

Using Light to Shift Your Schedule

In general, shifting your sleep and wake up times is difficult. That’s why we’ve incorporated specific tools to help facilitate the process.

Light is the most important tool in your efforts to shift your schedule. Exposure to light in the morning will help initiate the change to your new schedule. Getting light throughout the day will keep you alert.

What type of light is ideal? Sunlight is by far the best. After waking or at times that you should remain awake, try doing activities outside such as walking or exercise. If you cannot be outside – turn on relatively bright full-spectrum lighting indoors such as LED’s and fluorescent lights. Using light emitting devices such as phones and laptops can also be helpful.

For the evening hours – avoid light exposure 2 to 3 hours before the proposed bed time. If light cannot be avoided, we recommend using Blue Blocking Glasses (also developed by Somnitude). These glasses filter out the most alerting component of light and help transition your circadian clock to night mode.

Therefore, by controlling the timing of light exposure, you can trick your circadian clock.

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