Why do I feel so miserable after a long flight?
After a long flight across numerous time zones, you emerge from the airport exhausted and disoriented, a feeling you struggle to shake for the first several days of your trip. What is going on?
This all-too-frequent scenario for people who travel frequently is a result of two things: travel fatigue and jet lag. In this blog post, I will address jet lag, a condition that our smart sleep mask can help you overcome at 3x the natural rate. In a subsequent post, I will talk about travel fatigue and how to combat it.
What causes jet lag?
Jet lag is caused by a misalignment between your body’s hormonally regulated biological clock, or circadian rhythm, and the new time zone you’ve found yourself in. Numerous inputs help set your circadian rhythm, one of the major ones being light, namely sunlight. Light is received by non vision forming cells in your eyes, and this signal is communicated to a part of your brain called the SCN, which releases hormones like melatonin (which makes you sleepy) and cortisol (which helps you stay alert). Since it takes several days to entrain, or set, your circadian rhythm, when you physically step off that plane in a new time zone, your circadian rhythm will take several more days to arrive (typically one per time zone). The result: insomnia, fatigue, inability to concentrate, digestive problems.
As an example, consider my college friend Gabi, a beautiful person and amazing dancer who recently flew from her home in NYC to Poland to kick off a six week dance tour. Bedtime (~11 pm) and waketime (~7 am) in NYC are 5 am and 1 pm in Warsaw, respectively. So when Gabi stepped off her red-eye flight at 7 am, her body thought it was 1:00 am. Worse still, when night fell in Poland, her body felt that it was 3:00 in the afternoon.
What can you do about?
Prepare yourself: Help yourself out by easing into the new time zone before you depart. If you’re flying east, try to go to bed and wake up an hour earlier each night. For westward travel, stay up and wake up an hour later each day. Light exposure at the appropriate times of day can also help: more early morning bright light will help with eastward travel, whereas late evening bright light can help your body ease into a new later time zone. One issue is that these regimes can be somewhat cumbersome— bright light boxes can deliver the right intensity of light at the right time of day, but finding the time to sit in front of one for an hour each day is often a challenge. We are developing a smart sleep mask based on Stanford technology that can deliver light inputs during sleep in the form of millisecond pulses of light that are more effective than continuous bright light during waking hours.
Pick the right flight: My friend Gabi certainly didn’t help herself out by arriving first thing in the morning in her new time zone, likely exhausted from her all night flight. Many of us choose red-eye flights to try to maximize the time we have at our destination, but if you struggle with jet lag, this can be like shooting yourself in the foot. A better approach is to try to time your flight so that you are arriving in the late afternoon or evening in your new time zone so that there is less time between landing and bed time in your new time zone. This way when travel fatigue sets in, you don’t have to suffer through a day of exhaustion.
Get the right light exposure once you arrive: Daylight is a powerful regulator of the circadian clock, so getting light at the right time of day can help you adjust faster. A simple rule of thumb is to seek morning light for eastward travel and evening light for westbound travel. There are more sophisticated algorithms that predict optimal times to get light exposure to ease yourself into a new time zone, and we are working towards including these with our smart sleep mask to help you beat jet lag faster.
Other tips: Get some exercise, as it can help improve sleep quality… but not too close to bedtime, as that can make it harder to fall asleep. Be smart about your caffeine and alcohol intake. Caffeine has a 6 hour half-life, so think twice before using it to power through your afternoon. Alcohol can interfere with sleep in a variety of ways, so it may be best to forgo your evening glass of wine while you are adjusting.