Tuesday, 22 July 2014

Six sleep and jetlag tips

Bed time at the Hohenzollernbrücke Kölner Dom

Blogging has been light lately, I was at a workshop on statistics and homogenization in the USA. For me as old European this is another continent, 8 hours away. Thus I thought I'd share some jetlag tips, most of which are generally good sleeping tips as well. The timing is good: many people have trouble sleeping during the warm summer nights.

As far as I know, science does not really understand why we sleep. My guess would be: variability. Which is always my answer to stuff we do not understand. Most problems involving only the mean have been solved by now.

By doing the repairs and maintenance of your body at night, when there was not much else to do in the times before electrical light, you can allocate more energy to other stuff during the day and, for example, outrun someone who is repairing his cells all the time. Creating some variability in tasks between day and night thus seems to make evolutionary sense.

(The part I do not understand is why you have to lie down and close your eyes. Isn't is enough to simply rest? That seems to be so much less dangerous. But maybe the danger was not that large in bands where everyone has its own sleeping rhythm and someone is wake at most times.)

To differentiate between day and night, you need internal clocks to coordinate the action. Clocks that tell you to increase your cortisol in the hour before waking up, to get your body ready for action again. Clocks that tell you to reduce urine production during the night. Clocks that reduce the motility of your intestines while sleeping. Clocks that tell you to wind down and get ready for sleep in the evening. And so on.

These chemical clocks need to be synchronized, they do so mainly by light, but I have heard claims that also movement is signal for these clocks to keep track of the time. Without synchronization most people have an internal clock that runs one or more hours late and produces days that are longer than 24 hours. This natural period varies considerably. People who are night owls, most scientists for example, have longer internal days as early birds. I seem to be an extreme owl and can stay awake and concentrated all night. The rising sun is sometimes my last reminder that I really need to get to bed because otherwise my time becomes too much off with the rest of society.

1. Take your natural rhythm into account

Which brings me to tip 1. Or maybe experiment 1. For me as an owl, flying East is hard. It makes the day shorter and the days are already much too short for me anyway. In case of this last flight home, it made the day 8 hours shorter, not 24, but only 16 hours. Horror. Thus you have to go to bed well before you are tired and consequently cannot sleep.

My experiment was to stay awake during the flight. That made my day not 8 hours shorter, but 16 hours longer. Such a 40 hour day is probably too much for most, but given my natural long day, this seems to have worked perfectly for me. I hardly had any jetlag this time, almost like flying West, which also comes easy for me. I am curious what the experiences of others are. And can this trick be used by early birds flying West as well?

2. Light exposure

Light is vital for setting your internal clocks. Try and get as much sun as possible after your jetlag. Walk to work, take breaks outside, eat your meals outside, whatever is feasible. Often conferences are in darkened rooms, which mess up you clocks even without jetlag. Consider arriving early and spend your days before the conference outside.

Also on normal days, night owls should make sure that they get as much light exposure as possible and get outdoors early in the day to quickly tell your internal clock that it is day. It may help early birds to stay awake to seek the sun later in the day.

3. Artificial light

Artificial light, especially blue light, fools your internal clocks into thinking it is still day. If you do not become sleepy and have trouble getting to sleep, try to limit your exposure to artificial light in the evening. There are large differences in the color of the light between light bulb, select one that gives a nice warm glow and do not make the room too bright. The availability of artificial light is thought to have increased variability in sleeping times by making it easier for night owls to stay awake.

4. Blue glowing screens

Also monitors and smartphones give of a lot of blue light. I have f.lux installed on all my computers, it removes the blue light component from your monitor. I am not sure it helped me, but it cannot hurt in any way as long as the work you do is not color-sensitive. (If it sometimes it, you can easily turn it off.)

5. Pitch dark

Different Blindfolds for sleeping and resting
Make sure that your sleeping room is completely dark. This signals your clocks that it is night. Doing so improved the quality of my sleep a lot. They say this becomes more important as you age. Before putting blinders on your windows or hang up light blocking curtains, you can experiment and see if this is important for you by putting on a sleeping mask or simply lay a dark t-shirt over your eyes. (As an aside, also sleeping on a firm surface rather than a mattress improved the quality of my sleep I am curious whether other people have similar experiences.)

6. Sleep rhythm

The ideal nowadays is to sleep in one long period. This may be a quite recent invention to be able to use the evening productively using artificial light. Before people are thought to have slept a period after sunset, woke up for a few hours doing some stuff humans do and sleep another period. Even if this turns out not to be true, there is nothing wrong with sleeping in a few periods or with taking a nap. If you are awake, just get up, do something and try again later. I am writing this post in such a phase. Uncommon for me, probably due to the jetlag, I was tired at 8pm and slept two hours. When this post is finished, I will sleep the other 6 hours.

Related to this: try not to use an alarm clock. I realize this is difficult for most people due to social pressures. In this case you can set your alarm clock at a late time, so that you will often wake up before your alarm clock. Many people report waking up with gradually increasing light intensities is more pleasant, but also these devices are still an alarm clocks.

What do you think? Do you have any experience with this? Any more tips that may be useful?


  1. Flying most places from New Zealand is a trip north rather than east or west. We can choose to go either way to fly to the UK from here and it doesn't make much difference to the time which way we go.

    The jetlag is somewhat dependent on the season at the destination. If it's summer, then jetlag is less troublesome. If it's winter, then jetlag usually lasts longer. I guess because there are fewer sunlight hours to help your body clock adjust to the new time.

    In my experience, it usually takes a week to get completely over jetlag when flying from New Zealand or Australia to Europe.

    Your sleep tips are good. I definitely agree with the complete darkness. I would also add to these no caffeine after lunch. If I drink any tea or coffee after lunch I can't get to sleep. But some people are more sensitive to caffeine than others and I am one of them.

  2. Yes, this was a post for the Northern Hemisphere. I guess the warm summer nights are not your current problem.

    I am one of those that hardly respond to caffeine. I would almost guess that most Americans are as well. A waitress was very surprised I only drank one coke, with free refills 3 or 4 are more normal. Try sleeping after 4 cokes for diner.

  3. Just less than a year ago, scientists discovered that when we sleep, cerebrospinal fluid is cleaning waste products (from everyday neuronal activity) and toxins (such as Alzheimer's-causing proteins) from our brains. This is why we must sleep, and makes a lot of sense to me!


  4. Hi Lynne, thanks for dropping by, it was nice meeting you in Boulder.

    That is a nice idea about why we need sleep or about why we need variability.

    Nedergaard believes the clean-up process is more active during sleep because it takes too much energy to pump fluid around the brain when awake. "You can think of it like having a house party. You can either entertain the guests or clean up the house, but you can't really do both at the same time," she said in a statement.

    At night the brain cells shrink, making pumping cleaning fluid more easy. During the day I guess the full cell size is needed to think best. Always being in the mean state, thinking a little less well and cleaning being a little harder, is less attractive as variability.


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