Monday, August 07, 2017

Sleeping like a bird


Most of us know it: In an unfamiliar bed you don’t sleep well. At least not during the first night. From the second night on the insomnia is over. Maybe you think that it is because you are a nervous type of person. However, researchers of the Brown University have discovered that it’s normal and that most people suffer from it. It’s probably a relic from prehistoric times. They call it the “first-night effect” and they see it as a typical sleep disturbance when you pass the first night in a novel environment.
The researchers let a number of test subjects sleep in an unfamiliar environment and subjected them to several tests. I’ll spare you the details, which you find in source (1) below, but they found that the different hemispheres of the brain have different levels of activity during the first night of sleeping at an unfamiliar place, while the activity levels are the same during the next nights. To be exact, it was the left hemisphere that slept lighter and was more vigilant to external signals than the right when the first-night effect occurred. So, a soft sound will awake you during the first night, because your left hemisphere is watchful, while during the second night in the same bed you will continue sleeping and not hear it. You can see the enhanced vigilance of the left hemisphere also in an electroencephalogram of the two hemispheres: The left hemisphere shows more abrupt and short shifts during the first night when the effect occurs. The consequence is that during a first night in a novel bed you have a fitful sleep that leads to faster awakening upon detection of deviant stimuli by the left hemisphere of your brain.
Why does it happen? The researchers speculate that the regional asymmetry between the two brain spheres is linked with a protective mechanism that is sensitive to potential danger in an unfamiliar sleeping environment and with the increased need for vigilance during sleep. In other words, you never know whether there might come a lion or murderer into your room, so stay alert. However, when nothing special happens during the first night in a novel bed, your brain seems reassured and it doesn’t expect any longer that a danger will show up. Actually it’s a bit strange, for as soon as a lion or murderer has learned about this mechanism, for example from own experience, he might get the idea that it’s best to drop by not during the first night but later. It will give more chance of success. But apparently, in prehistoric times it worked and we survived, or at least those survived who got it in their genes. That’s why we are now cursed with it, although we no longer need it and although actually it has become a bit annoying. It belongs now to the human constitution. And not only to the human constitution, for you find this unihemispheric sleep as a protective mechanism also in some birds and marine mammals, so that they can monitor their environments and detect predators when sleeping. To say it tersely: In a novel bed you sleep like a bird.
How sad for me, for when I go on holiday, I often travel around and stay no longer than one or two nights at the same place. When touring about with my tent, you can say that the bed remains the same and that only the environments change, but when moving from hotel to hotel, each night or two nights means another bed. It involves much insomnia. However, it seems that travellers can become accustomed to the phenomenon of the unfamiliar bed and that the first-night effect disappears. Anyway, during a travel I gradually sleep better. But basically there are no solutions for the first-night effect. Maybe it helps to arrive a few days before an important appointment if you need to spend the night in a hotel. It might also help to take familiar things from home with you and put them next to your unfamiliar bed, or to take your own pillow with you. They may make you feel at ease. Sleep well and good night.

Sources:
(1) Masako Tamaki et al., “Night Watch in One Brain Hemisphere during Sleep Associated with the First-Night Effect in Humans” in Current Biology, http://www.cell.com/current-biology/fulltext/S0960-9822(16)30174-9
(2) “Scientists reveal why we sleep poorly the first night we stay in an unfamiliar place”,
 (3) “Sleeping away from home? Half your brain is still awake”, https://www.newscientist.com/article/2085409-sleeping-away-from-home-half-your-brain-is-still-awake/