It’s so difficult to help your child adjust to a socially normal bed and wake at home, so the prospect of traveling across time zones with a baby or toddler 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 country with little drama. Note that travel can be complicated beyond jet lag. For more tips and tricks, check out our travel survival guide here.
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 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 to the clock in order 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 the 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 synch 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. 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 at different times of day does different things. Light in the morning shifts sleep earlier, while light in the evening shifts everything 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 light the effect of light reverses. The figure below illustrates this change.
This is 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.
Traveling 1-3 hours westward
First, ask yourself, do you have to shift your child? There are some situations in life where it may be possible to allow your child to remain on your old time zone. For example, if you are taking a trip that lasts less than a week or if you are only traveling one time zone, then it will be easier for your child if you just keep your watch set to your old time zone and put your child down at his biological bed/nap times.
The charts below show your child’s biological time and the relative clock time in a one-hour time zone change, a two-hour time zone change, and a three-hour time zone change. The most important thing to do when shifting your child’s sleep pattern is to ensure that you control his light exposure.
How to use these charts:
Print the blank chart (at the bottom of this blog) and shade in your child’s normal sleep timing in the line under your home time zone.
Pick the adjustment speed that suits your child’s age and shade in subsequent days to plan your child’s adjustment (e.g. for a 5 month old, you would shade in 15-30 minutes later adjustment per day).
When you arrive at your destination, put your child down relative to the new time and adjust based on your schedule.
If you need your child to adjust right away, begin shifting your child before your trip.
Sample Adjustment for a 4-12 month old. Babies in this age range can usually handle a 15-30 minute shift in the circadian rhythm each day. Notice that wake time DOES NOT SHIFT as fast as you shift bedtime. Full adjustment will take 3-4 extra days to achieve a stable wake time. It is ok to go to your child if he wakes earlier than socially normal, but be sure to keep it DARK until your child’s new target wake time even if your child is not able to sleep in the morning.
Sample Adjustment for a toddler over 12 months. Most toddlers will be able to handle a 30-60 minute shift each day. Notice that wake time DOES NOT SHIFT as fast as you shift bedtime. Full adjustment will take a few additional days to achieve a stable wake time. It is ok to go to your child if he wakes earlier than socially normal, but be sure to keep it DARK until your child’s new target wake time even if your child is not able to sleep in the morning.
How do you manage naps during westward travel?
Naps are NOT controlled by the circadian rhythm, so you have a considerable amount of flexibility to nap your child at slightly off hours, while still maintaining the biological shift at night.
If your baby is under four months and has a somewhat unpredictable sleep pattern, then simply make sure you continue to give your baby nap opportunities about every two hours while you are away.
If your baby has a stable nap pattern, then the best thing to do is to offer naps adjusted by the same amount of time as bedtime. For example, if you are moving bedtime later in 15-minute increments, then start at your child’s biological nap time and shift naps by 15 minutes each day.
It’s important to note that you can strategically use “off” napping to your advantage. For example, if your child stays awake for too long between naps (which often happens during busy days of travel), then you can let him take a nice long, late nap. If this happens, then you will need to wake him up after a few hours. This means you’ll be able to put him down a lot later in the evening, which will allow him to have extra light exposure before bed. This will help shift him faster.
Once again, it helps to work through an example to understand. Imagine you are traveling from Boston to San Francisco and imagine that your baby normally goes to bed at 7:00 Boston time, which is 4:00 in San Francisco. If your baby doesn’t sleep well in the early afternoon due to excitement, but then falls asleep at 3:00 PM San Francisco time, you can let him sleep until 5:00 and then put him down for the night at 7:00 PM (which is a socially normal time!). There is a catch though – this manipulation will not make his bedtime stick at 7:00 on future days. In the absence of a long, late nap the next day, you will need to “jump back” to an earlier social bedtime the next night.
Example of nap manipulation. In the scenario below, on day three the baby got a little catnap around the time when the second nap should have been and ended up taking a long, late nap. This allowed for a later, more socially normal bedtime on that day, but it would not have been sufficient to truly shift the circadian rhythm later (as evidenced by wake time remaining early). On day 4, when naps were early again, bedtime had to jump back to an earlier clock time to account for the true biological adjustment.
What should you do to help your child shift eastward when returning home?
We have a blog for that! Check it out here.
We know that travel can involve all sorts of other chaos. Check out our general travel tips in this blog. If your child regressed during travel, then we are here to help! Feel free to set up a consultation with us and we will help you get back on track.
Print the chart below to plot out your own westward jet lag plan.