Have Trouble Sleeping In Hotel Rooms? Blame Evolution
If you travel for work, you’re probably familiar with what sleep researchers call “first night effect” or FNE, which simply means that many of us consistently have a difficult time sleeping during the first night in a new place, commonly a hotel room. Turns out this annoying part of travel reveals something interesting about how our brains function. Working from previous research involving the brains of dolphins and birds, a research team from Brown University wanted to find out if FNE is an evolutionary remnant rooted in our brains’ hardwired self-defense mechanisms.
Dolphins, whales, birds and a few other species are able to put half of their brains to sleep at a time to ensure that they’re never entirely at the mercy of predators. One half snoozes, the other stays on guard. The effect is so pronounced in birds that they actually sleep, like the old saying goes, with one eye open. Until recently human brains didn’t seem capable of the doing the same, but the researchers in the latest study theorized that perhaps a similar half-and-half sleep system is the reason why we so often toss and turn that first night away.
To find out, they studied a group of 35 participants recruited to sleep for two nights at Brown’s Department of Psychological Sciences. Their brains were monitored during both nights with neuroimaging tools, including MRI, and their eye and muscle movements and heart rates were also tracked.
As predicted, the participants slept less well the first night than the second. They took twice as long to fall asleep and their eye movements and heart rates indicated less restful sleep. More surprisingly, the research team found that during the first night only, the left hemispheres of the participants’ brains didn’t sleep as deeply as their right hemispheres–suggesting that a “unihemispheric effect,” similar to that of dolphins and birds, played out during the first night of the experiment.
To find out if the participants’ left hemispheres were staying alert to process information, the researchers conducted a follow-up experiment in which they played a series of timed beeps while the participants slept. Regularly timed beeps of the same tone played throughout the night, with smatterings of irregularly timed, differently toned beeps tossed in. If the participants’ left hemispheres were staying alert to monitor the room for anything odd during the first night, they should react to the irregular beeps–and that’s exactly what happened. The left hemispheres showed more activity and the participants were restless in response to the random beeps the first night; the effect disappeared the second night.
While the effect isn’t as distinct as it is in dolphins and birds, the study shows that our brains appear to be on night watch the first evening we’re in a new place. According to corresponding study author Yuka Sasaki of the Department of Cognitive, Linguistic and Psychological Sciences at Brown University, “Our brains may have a miniature system of what whales and dolphins have.”
All of this may be of little consolation the next time you’re struggling for shuteye in a hotel room, but it’s more evidence that we aren’t so different from other species, no matter how nice a king-size bed we sleep in.
The study was published in the journal Current Biology.
