Bryan Caplan  

Jet Lag, Night Feedings, and Fixed Costs

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Economists usually emphasize marginal analysis.  Should a firm make one more pound of steel?  Should a shopper spend one more minute looking for a lower price?  But economics has just as much to say about all-or-nothing decisions.  If a firm has to pay a fixed cost to stay in business, it shouldn't just weigh the costs and benefits of making another pound of steel.  It should also weigh the costs and benefits of making any steel.  If a shopper has to pay a fixed cost to get to the store, similarly, he shouldn't just weigh the costs and benefits of another minute of search.  He should also weigh the costs and benefits of going to the store in the first place.

As a generality, this is all pretty obvious.  But applying this generality is harder than it looks.  Here are two practical decisions where it took me a while to figure out the optimal response to the fixed costs I faced:

1. Jet lag.  What's the best way to cope with jet lag?  Most people sleep on the plane, then gradually adjust to the local time once they reach their destination.  The problem: It often takes a week for people to get a decent night's sleep.  By the time they're feeling themselves again, they're almost ready to go home.

My alternative: Do not sleep on the plane.  At all.  When you arrive, do not sleep - at all - until a locally normal bedtime.  Pay the fixed cost without cheating.  When you wake up eight to ten hours later, you will be refreshed and in sync with your new time zone.  In exchange for less than a day of sleep deprivation, you will feel fine for the rest of your trip.

2. Night feedings.  Newborn infants typically sleep in 2-4 hour blocs.  When they wake up, they usually need a new diaper, and almost always want to eat.  Most parents handle this by sleeping whenever they get the opportunity, then waking up when the baby starts crying.  Many go one step further and "takes turns" for night feedings out of some sense of fairness.

As long as you have two available care providers, the conventional approach is extremely imprudent.  What's the alternative?  One care provider should pay the fixed cost to get on a nocturnal schedule.  After a day or two, the person on the night shift adjusts to sleeping during the day, allowing the other care provider to sleep through the night without interruption.  Instead of "fairly" "sharing the pain," you're cleverly slashing the total amount pain down to a manageable size. 

Yes, switching to the night shift hurts at first.  I should know - I'm going nocturnal for natalism right now!  But after a day or two the whole family will feel fine - and you'll have basic economics to thank.


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COMMENTS (12 to date)
Jason writes:

I used the approach you described for night feedings with my son. My wife had the day shift, and I took the night shift. My proposed method actually consisted of three eight-hour shifts. 8 hours sleep, 16 hours awake, 8 of which you are alone with the baby, and the other 8 both parents are awake. We were obviously physically tired (who isn't dealing with a new baby), but at least we got our sleep. I'm expecting another baby in a few months time, I honestly don't know if it's going to work so well again, but I can tell you I'm definitely going to try.

Bob Montgomery writes:

As an expectant father (expecting my 5th in about a week) this is interesting.

But don't you have to go to work during the day? And does your wife breastfeed? Sorry if this is getting too personal.

What we've done for night feedings in the past:
I usually get up, get the baby, change the diaper, and bring the baby to my wife, and then go back to sleep. She then nurses the baby and then puts it back to bed.

I go back to sleep pretty easily, so it works out that I get up for 10 minutes twice a night, which isn't great, but isn't bad. It's worse for my wife, but she takes it easy during the day.

Seems like it goes down to just one nighttime feeding after a week or two and usually by 6-8 weeks the baby is mostly sleeping through the night.

The problem with switching to nocturnal schedule is that I will only be home for a week and then I have to go back to work, so I'd have to switch schedules twice in a week; seems like that'd be worse than just getting poor sleep for a few weeks. Something to think about, anyway.

Venu writes:

My alternative: Do not sleep on the plane. At all. When you arrive, do not sleep - at all - until a locally normal bedtime.

You have assumed that people can control when they fall asleep just through their willpower - but you cannot delay or advance sleep patterns just out of sheer willpower. In any case even if you manage to have one night's sleep does not mean your internal body clock has adjusted yet; you may still go back to irregular sleep patterns the next day, as the body clock shifts phase no more than 1-2 hrs per day in the absence of strong interventions.

Looking at the top results on Google scholar for "avoiding jet lag" suggests two strategies for minimizing jet lag: exposure to bright light at critical times and administering melatonin (a hormone that advances the body clock); see this editorial in BMJ and this article (pdf).

Erich writes:

I appreciate the tips, Venu, though I will also leave my anecdotal support to Bryan's notes below.

Recently, I did have success avoiding jet lag by altering my sleep schedule before I left and avoiding significant sleep on the plane.
Specifically, I stayed up to 3am, slept a handful of hours, took a 14 hour flight with no prolonged sleep, stayed up until the local bedtime, and crashed hard thereafter. I felt fantastic the day following each leg of the journey.

I admit, my youth and health significantly helped, but hope that Bryan's and Venu's tips will assist other travelers on their longer journeys.

Kurbla writes:

I do the same thing as you do in airplane - I always make period without sleeping longer, not shorter. Working in the shifts is more complicated situation - day without sleeping is every fourth day or so.

I have found by experiment that the best way to stay awake in the moments of crisis is - to dance on loud disco music.


Zac Gochenour writes:

FWIW, I agree with the not sleeping on the plane bit but not the "go to sleep at locally normal bedtime" if you can help it. Unless it is a very extended stay, I find it easier to simply stick with your usual bedtime and ignore what others are doing. I travel frequently to the Pacific time zone for work, but I live in Maryland; my home bedtime is around 1AM and my travel bedtime around 10PM. No adjustment necessary.

This would be harder, I think, were I traveling to Europe. In that case, I second Bryan's recommendation. Also re: Venu, I take melatonin supplements when necessary and sleep with the blinds open. It helps that when I travel I need to wake around dawn.

Joe writes:

Our family solution to night feeding:
Breast feeding!!! My wife took the night shift!!
When she stopped and went back to work: disorganization!!!

I must echo the chourus of people saying that the jet lag plan isn't necessarily best. Back in June I flew to Berlin without sleeping on the plane at all (this wasn't a choice, however, I can't sleep on planes). We arrived in the morning and managed to stay awake until that evening. And it worked fine. However, I just returned last Saturday and I tried the same plan. Oddly, however, the next night I didn't sleep at all, as I had not adjusted. Needless to say I did not have fun in class on Monday morning!

eccdogg writes:

Second Bob Motgomery on the day shift/night shift thing.

If your wife breastfeeds she pretty much needs to be there at night and if you are working you can't be there during the day.

If she pumps you can start adding bottle feedings by you at about week 2, but still you need to stay up at night and work during the day. I guess you could do 8 hours at night 8 hours at work then sleep right when you get home.

My wife and I just had a baby the same day as you, and I just went back to work today and we are using the same strategy as Bob Montgomery. I change diaper and bring baby to my wife and she puts the baby back to bed sometimes I burp the baby. One nice thing we learned with our first and are now doing with our second is to get a co-sleeper so the baby is (safely) in bed with us. That way my wife does not even need to get out of bed.

Stan Greer writes:

Bryan, the "radical" solution few want to discuss, but many furtively opt for:

Keep the nursing baby in bed with you, and then mom can feed the baby without getting out of bed. Once the baby gets experienced enough to nurse efficiently, he or she may well be able to get in a good late night/early morning snack without waking up mom or dad at all.

I realize this doesn't apply to you, personally, since you are bottle feeders, but it is a choice many breast-feeding families opt for. Most don't talk about it, because of the supposed "dangers" of co-sleeping.

My wife has breastfed six children in bed so far, and neither she nor I has killed any of them yet! And if you aren't grossly overweight, don't get drunk, and don't get whacked out on other narcotics, you won't kill your baby, or hurt your baby in any way, by co-sleeping, either.

Stan Greer
Fairfax, VA

Patrick writes:

If you need to adjust your sleep schedule
FAST!

The "I am hungry, is it breakfast yet?" takes precedence over sleep. You can adjust your sleep schedule by simply not eating for 16+ hours. When you eat again, that will be your new breakfast time.

rockpool writes:

The night shift/day shift plan only works if one person can sleep during the day. Don't know about your baby, but my twins were pretty nap-averse during the day.

I think next time I will try co-sleeping, assuming breast-feeding goes well. I'll let you know how it works out with my mini case/control study come March, when I'm due to have baby number three.

I'm a big fan of Melatonin for jet lag.

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