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Car Cat Naps: Is It Sleep Deprivation or Something Else?

How driving may make you feel sleepy.

fizkes/Deposit Photos
Source: fizkes/Deposit Photos

When I was first dating my wife, she would fall asleep on any car ride that was longer than about 15 minutes. My daughter is now the same way. At first, I thought it was just that they were tired, or bored.

This week, I decided to explore this interesting topic and one that I have given considerable thought to over the years. Recently, there has been a fascinating new research study from Australia which sheds new light on this topic.

Historically, I used to think that many people who would fall asleep either while driving or as a passenger in a car were either bored, sleep-deprived, or afflicted with something called Sopite Syndrome. Sopite Syndrome is a variant of motion sickness where you don’t feel sick, but rather you get sleepy when moving. This could have something to do with your vestibular system (balance in your inner ear).

However, this new study has shed new light on this very topic. Researchers were able to discover that it is the vibrations at low frequencies (like we experience when driving cars or trucks) that over time make us feel more and more drowsy. This makes perfect sense to anyone who has a small child who would only fall asleep when driving them around the block late in the evening!

More specifically, these researchers discovered that levels of alertness after driving for only 15 minutes begin to decrease dramatically, and by 30 minutes will have a significant impact on your ability to stay alert and concentrate on the road. By 60 minutes, sleepiness is at its peak. These researchers think that there are vibrations that can keep you awake as well, and further study is required.

So what should we all do with this new piece of information?

  • If you are going on a drive for longer than 30 minutes and you feel sleep-deprived, consider a carpool, rideshare, Uber, or bringing a friend so you can switch off every 30 minutes.
  • Consider small doses of caffeine 15-25 minutes prior to a long drive, and every 2 hours after. But remember not too close to bedtime!
  • Get direct sunlight each morning and just before driving to help keep you awake.
  • Follow a regular sleep schedule so you can decrease your sleep deprivation.

Understanding how driving may make you feel sleepy is certainly an important thing for all of us to be aware of; however, what if you need to become sleep-deprived (due to an unusual circumstance)? Are there some people who are better at being sleep-deprived than others? It looks like the answer is yes.

Doctors think that they may be getting closer to understanding who can function best on low levels of sleep. Research shows that lack of sleep seems to affect different people in different ways, as we all know there are some people that just seem to “take” sleep deprivation better than others. I had a roommate in college who could do an “all-nighter” no problem and be fine the next day. I will admit, I was a bit jealous.

A few scientists think they may know why, and the answer is in your genes.

A group of researchers from the University of Pennsylvania did an interesting experiment where they took 32 people and monitored them for 5 days: consisting of 2 nights of 8 hours of sleep, and then followed by 39 hours of no sleep—i.e., total sleep deprivation. Researchers measured miRNA levels using blood samples. They also tested several types of cognitive abilities, including attention, memory, and cognitive throughput performance (how fast and accurately people completed the tests).

miRNAs molecules are small bits of genetic material that regulate gene expression. They typically work by preventing messenger RNAs from turning the information stored in genes into functional proteins.

So what is the practical information you can get out of this study?

It's genetic: If you have never been bothered by low levels of sleep, it seems to be something you are born with, not something you can train your body to do.

As a side note, even if you do not “pull an all-nighter,” these researchers discovered that if you sleep only four hours a night for five nights in a row, the same consequences occur.