Travel Survival Guide: Traveling 4-8 Time Zones westward

It's often hard to get your baby or toddler to sleep well at home, so the prospect of traveling across time zones can be daunting. We won’t say that adjustment to jet lag is easy, but your child’s circadian rhythm is designed to be flexible, and given time and careful control of light and darkness, your child can adjust to a trip across the globe with little drama. This blog covers how to handle westward jet lag of approximately four to eight hours, such as traveling from London to New York or San Francisco or from Boston or LA to Hawaii.

Since most families will return home after travel, also check out our guide for traveling 4-8 time zones eastward to plan for both legs of your journey. If your travel involves jet lag of 1-3 hours, then check out our other blogs on eastward and westward jet lag.

The Science. A quick warning about this science section; it’s complicated. We’ve tried to simplify it, but if you find your head spinning don’t worry. Many university-level students of circadian biology have trouble with this topic in the beginning. You can just skip to the jet-lag plans below and follow them without knowing the science if needed!

Jet lag is so-called because with the invention of air travel humans became able to rapidly cross time zones faster than our internal body clock (or circadian rhythm) could keep up. The “lag” in jet lag refers to the time that it takes for your circadian rhythm to catch up to socially normal bed/wake/eating times in a new time zone.

The circadian rhythm is flexible and makes small adjustments every day even when you stay in the same time zone, because the circadian rhythm for about 70% of people is a little longer than 24 hours (about 30% have a circadian clock that runs a little shorter than 24 hours). This means that your child’s (and your) circadian rhythm has to make a small adjustment each day to keep biological time in synchrony with the 24-hour day. Think about it like this, your body clock is like a watch that runs about 12 minutes fast. Every morning when you wake up, you have to readjust your clock, so that it keeps accurate time.

How does the circadian rhythm reset? It happens through the timing of your daily light exposure through your eyes (your eyes have to be open for it to work). If you weren’t exposed to light in the morning, then your biological bedtime and wake time would start to drift later and later every day. Babies are not born in sync with the 24-hour day and if you plot your baby’s sleep from birth you may see this type of shifting pattern, where the longest sleep bout doesn’t stay at night (you can learn more about newborn sleep here or in our 0-6 month class). Similarly, some people who are totally blind aren’t able to synchronize and develop a disorder called non-24 sleep-wake disorder, where the circadian rhythm just keeps following its own clock and cannot be reset to social time.

When you travel across time zones the same adjustment process will happen, BUT since the timing of light exposure (sunrise, sunset) relative to your child’s body clock will be off, the timing of light exposure could actually make things much worse. Why? Because light does different things at different times of day. Light in the morning shifts sleep and wake earlier, while light in the evening shifts sleep and wake later, but of course “morning” and “evening” are relative to your child’s body clock, NOT your watch. In addition, during the biological night there is a transition point where the effect of light reverses. The figure below illustrates this change (note that the change won't happen at exactly 3:00 am but it's usually around that time for most children).

This is why we cringe when parents tell us they turn on lights in the middle of the night! This is also why jet lag is hard. You have to think about what time it is in your child’s body and control light exposure relative to that time.

Finally, it’s important to know that the circadian rhythm is one of the two sleep drives (see basics on sleep here), but it also controls a great deal of other biological functions including hormone production, urine excretion, cognitive function and it also plays a role in meal timing. This means that when your child is jet-lagged, it’s not just sleep that will be off – everything will be off.

Why is westward jet lag hard?

Westward jet lag will involve pushing your child's sleep timing substantially later than normal. If you try to force your child to follow his/her sleep schedule on local time when you arrive at your destination, your child may be overtired at bedtime and will likely have trouble maintaining sleep in the second half of the night.

This is best illustrated through example: imagine that your child sleeps from 7:00 pm to 6:00 am. If you are traveling westward, say from London to Boston, putting your child down at 7:00 pm in Boston will be the same as keeping your child up until midnight because 7:00 pm in Boston is the same time as midnight in London. You would probably never force your child to stay up so long under normal circumstances.

While your child will likely be able to fall asleep at 7:00 pm Boston time in this scenario, it's unlikely your child will stay asleep. This is because 6:00 am in London (your child's wake time) is 1:00 am in Boston. This means your child will probably be wide awake at 1:00 am and won't easily be able to fall asleep again, potentially for hours. Even if your child doesn't eat at night, your child will probably be hungry during the night due to it feeling like morning in his/her body.

What can you do to help your child adjust to 4-8 hours of westward travel (e.g. Europe to the US)?

• Start with an early bedtime and gradually shift later. This isn't a hard rule, but if you can, it's usually best to start with an early bedtime that better aligns with when your child's body is ready for sleep. For example, if your child normally sleeps at 7:00 pm, you might start with a 5:00 pm bedtime on the day you arrive and push 30 minutes later each day until you are putting your child down at 7:00 pm local time.

• Maximize afternoon/evening light exposure. Remember, light in the evening will shift your child's drive to sleep later. Take your child outside in the afternoon/evening to maximize natural light exposure. Your child's circadian rhythm won't adjust without evening light exposure.

• Keep it DARK until your target wake time. Remember light in the morning will keep your child's circadian rhythm stuck in the time zone where you started. Make sure you keep it as dark as possible until the time you would like your child to be awake.

• Plan for night waking. Expect your child to be awake for hours during the night, especially at first. You don't have to force your child to stay in bed (in fact, most children probably wouldn't be able to stay in bed while wide awake), so make a plan for what you will do when your child wakes up. For example, play quietly with toys that glow or read books with a nightlight level light. If your child is older and you allow screen time, put a children's program on your phone or tablet and set it a few feet away from your child to prevent light from the screen from impacting your child's circadian rhythm.

• Keep "extra" night feedings minimal. Your child may be hungry at night because the middle of the night will feel like morning to your child. If your child doesn't normally eat at night, offer a small snack or feeding. You may need to gradually reduce feeding duration amount over time as described in this post.

• Manage naps. Your child will likely be exhausted in the afternoon because that time will correspond to bedtime in your original time zone. You'll need to wake your child from afternoon naps to prevent the nap from becoming a super early bedtime (e.g., if your child sleeps from 3:00 pm until midnight, you'll probably be up for the rest of the night!). It's ok to let your child sleep a little longer than usual for naps. It's also ok to let a child who doesn't typically nap take a nap during this adjustment period. If your child is in the midst of a nap transition, review our nap series to make adjustments.

• Pack smart. Review our travel survival guide for other suggestions about what to bring on your trip.

Determine your approach based on the length of your trip:

Consider a “compromise” sleep shift for short trips. There are some situations in life where it may be possible to partially shift your child in order to minimize the amount of disruption you will have during your trip and on the way back. For example, if you are taking a short trip to a relative’s house, then it will be easier for your child if you just keep your watch set to your old time zone and aim to have your child down a times near his biological bed/nap times. This works well for destinations like Hawaii because your child will be up early but you can be outside early to enjoy the sunrise and quiet time on the beach :)

Need more help?

We are moms with formal education in sleep medicine, nursing, and behavior analysis. If you don't want to build a jet lab plan on your own, book a one-on-one consultation with us and we'll map out a plan for you to follow.

We always appreciate it when you share our blogs and resources with other parents who could benefit from the information. If you need a little help to figure naps out or if you are facing other challenges, then please check out our other blogs, our 0-6 month class, and sleep training class. We have blogs on schedules, travel, toddler issues, and more! If you just need to talk to someone who can help you devise a sleep plan, then feel free to book a one-on-one consultation with us. We are always happy to help!

References

Czeisler, C.A., Duffy, J.F., Shanahan, T.L., Brown, E.N., Mitchell, J.F., Rimmer, D.W., Ronda, J.M., Silva, E.J., Allan, J.S., Emens, J.S. and Dijk, D.J., 1999. Stability, precision, and near-24-hour period of the human circadian pacemaker. Science, 284(5423), pp.2177-2181.

Sack, R.L., 2010. Jet lag. New England Journal of Medicine, 362(5), pp.440-447.

Arendt, J., 2009. Managing jet lag: Some of the problems and possible new solutions. Sleep medicine reviews, 13(4), pp.249-256.

Roach, G.D. and Sargent, C., 2019. Interventions to minimize jet lag after westward and eastward flight. Frontiers in physiology, 10, p.927.