Do you always seem to lose sleep when you stay over at a friend’s place or on the first night in a hotel – no matter how luxuriously perfect the bed feels?
If that’s the case, you’re most definitely not alone. In fact, you have at least one person to share the problem with – me!
This always seems to happen to me on the first night in an unfamiliar bedroom. So I know how frustrating it can be, especially if you have an important event the next day.
I used to think it was simply due to unfamiliarity with the new surroundings or perhaps some excitement about being on the road again.
But some interesting research into what’s sometimes called the ‘first night effect’ suggests a deeper explanation.
First Night Effect
When people spend a couple of nights in a specialist sleep clinic to check for sleep disorders, sleep experts have long known they can’t always rely on the first night’s data. And the patients themselves sometimes say they can’t sleep in a way that mirrors what’s happening at home.
Back in 2014, researchers from the University of Budapest looked into this first night effect more closely. They studied 27 people in a laboratory setting and found significant differences in sleep quality between the first and second nights.
On the first night, people took longer to get to sleep, slept for a shorter period, woke up more often and had less of the important restorative phases of sleep.
12 of the people studied also routinely suffered from nightmares. And they found that this group had even greater differences in the sleep parameters between the two nights.
The evolutionary theory
So why is it that so many people struggle to sleep in a different bedroom, even if they normally sleep well at home?
One theory is that poor sleep on the first night in a new environment is a natural, evolutionary self-defense mechanism.
It’s argued that your brain decides that a new place can mean extra danger to you, so a part of your brain stays alert. You could say it’s keeping watch while you rest.
In ancient times this could have been vital for self-preservation. Moving from a safe spot to a new and unfamiliar area could increase the danger from wild animals or other humans. This probably required early humans to be much more alert, even when sleeping.
In April 2016, researchers published a study of the first night effect using advanced neuroimaging techniques and polysomnography.
They studied 35 people sleeping in new environments, measuring brain activity on the first night and subsequent nights.
They focused their attention on the slow (Delta) wave part of the sleep cycle. This part of the sleep cycle is when we’re in our deepest sleep, and is also an essential restorative phase of sleep.
One half of the brain stays more alert
The researchers found that the left-hand side of the brain appeared to stay more active than the right-hand side on the first night. However, in the following nights there was little or no difference in activity between the two sides.
The brain also reacted much more to external noise on the first night, resulting in more awakenings and a faster behavioral reaction to the noise stimulus.
To test this, while people were sleeping the researchers played noise into their ears. On average they woke up more than three times more often on the first night than on the second.
Figure 1 below shows the average number of awakenings over a five minute period on the first night and then on the second night.
The researchers also tested what would happen if they only played the sound into the right or left ear of the sleeping people.
Figure 2 illustrates that there was a big difference in the percentage of times people woke up on the first night, depending on which ear the noise was played into. But there was no significant difference on the following night for both ears.
The researchers also found that the reaction time between hearing a noise and waking was significantly faster on the first night.
So perhaps after the first night without any real threats in the sleep environment, the brain can relax and let you sleep more soundly.
In line with the previous research, the team found that the average time it took people to fall asleep was much longer on the first night than subsequent nights.
The research suggests that the subjects were naturally staying more alert on the first night, perhaps so that they could wake up more easily if needed.
Interestingly, scientists have found that some marine mammals such as whales, dolphins and seals, as well as some bird species, have what’s called unihemispheric sleep, in which one side of the brain sleeps while the other remains alert.
This serves particular needs, such as allowing migrating birds to fly continuously for long periods of time, for marine animals to surface to breathe, and perhaps to stay alert to predators in some cases.
This level of unihemispheric sleep was long thought not to occur in humans. You were either asleep or awake, so to speak.
In 2019 a team of researchers further explored the idea that something similar might be happening in people during the first night effect. And they discovered that the two brain hemispheres weren’t always as synchronized as previously though.
As the study leader explained in phys.org:
Since different sleep stages are associated with different degrees of synchronization, I believe that some weak form of uni-hemispheric sleep, i.e., different sleep depth of the two hemispheres, can well occur in humans, not only in whales, dolphins, seals, and migratory birdsEckehard Schöll
Back to my own experience, and I’m pretty sure that if this is what’s happening when I’m on holiday, it’s not due to migration or a need to breathe while swimming! So it’s back to the theory of my brain looking out for me while I sleep.
I can’t help but wonder then if the level of security you feel in a hotel, friend’s house or holiday rental would make a difference.
Maybe I’ll string up some empty cans by the front door next time to see if that can reassure my half-asleep brain…
Have you noticed this first night effect? Perhaps you have a technique that helps you sleep when traveling? Let me know in the comments!