Jet Lag Key 1: Time Your Light Exposure
KEY POINTS:
1. Jet lag is a desynchronization between internal and external cues. The culprits of this desynchrozation lie in the brain and are known as the suprachiasmic nuclei (SCN).
2. The SCN is hugely affected by sunlight. Therefore, critically timed light exposure may help ease jet lag symptoms and speed up circadian synchronization.
3. Natural light exposure is the ideal mechanism for counteracting jet lag. However, light therapy (including a light box, lamp, or light visor) is an effective alternative.
4. Light exposure in the morning advances your circadian rhythms (you’ll sleep earlier), while light exposure in the evening delays them (you’ll sleep later).
I’m going to offer several tips or keys to lessening jet lag over the next few weeks. As professionals who cross time zones, you may know some of these. My goal is to explain the science behind the solutions and offer as many options as I can to support your health, which includes getting quality sleep.
The first key is to time your light exposure.
Jet lag arrises when there is a desynchronization between internal and external cues. The culprits of this desynchrozation lie in the brain – specifically the hypothalamus – and are known as the suprachiasmic nuclei (SCN). These nuclei regulate circadian oscillators by using visual information sent from the retina.
The SCN is hugely affected by sunlight. Therefore, light exposure unassumingly plays a massive role in the synchronization of our biological rhythms to external time by altering clock genes. Research indicates that critically timed light exposure of sufficient intensity may help ease jet lag symptoms and speed up circadian synchronization. More specifically, light exposure during or near our body’s cyclical minimum core temperature (all of us cool down during the 24-hour cycle) produces the greatest phase shifts.
Natural light exposure is the ideal mechanism for counteracting jet lag. However, for individuals who travel a lot, light therapy (including a light box, lamp, or light visor) is an effective alternative.
How does it work?
Light exposure at your lowest body core temperature (usually the middle of the night at home) and light avoidance at your highest core temperature (usually mid day at home) serves to essentially stop your circadian clock. Light exposure will also inhibit the release of melatonin: the more light, the less melatonin we produce. We get sleepy in the evening when the sun goes down because darkness stimulates melatonin. These biological rhythms operate in concert. For this reason, exposure to bright light coupled with melatonin use at the right time has been effectively shown to alleviate jet lag by synching our bodies to destination time faster (we’ll discuss melatonin supplementation in the next post).
How do I time my light exposure?
Light exposure in the morning will advance your circadian rhythms (you’ll sleep earlier), while light exposure in the evening will delay them (you’ll sleep later).
Eastward travel generally causes difficulty in falling asleep due to phase advances (your body is behind the local time zone) while westward travel interferes with sleep maintenance due to phase delays (your body is ahead of the local time zone).
EASTWARD TRAVEL
If you are travelling eastward, try advancing your sleep time by one hour per night three days prior to travel, and expose yourself to bright light upon rising. Upon reaching your destination, work to advance your rhythms (helping you to get to sleep earlier) by exposing yourself to morning and afternoon light and avoiding evening light at your destination. Expose yourself to bright light earlier by one hour per day at your destination to continue fostering adjustment throughout your trip.
WESTWARD TRAVEL
If you are travelling westward, try delaying your sleep time by one hour per night three days prior to travel. Upon reaching your destination, it is suggested that you delay your rhythms by exposing yourself to evening light and avoiding exposure in the early morning.
Today's 1% Tip: How to time your light exposure
1. If you're travelling east across time zones, you should get to bed earlier than usual for three days before you leave.
2. If you're travelling west across time zones, you should get to bed later than usual for three days before you leave.
3. Either way, help yourself to change your sleep patterns by using or avoiding bright light as you make the adjustments.
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