Source: Unsplash

The melancholy and monotony of daily life can sometimes really get to us. So we need to change things up a bit. Changes like renovating your house, getting some new furniture, or changing your routine. Of course, you don’t need to spend a lot of money for a change, getting a pillow change and sleeping with it will do.Routine

But for some people, changing pillows can be a big problem. Because for some people, they have a hard time sleeping when they use a new pillow. Still this is a case by case basis on “Why do some people have a hard time sleeping with a new pillow why some others don’t?”


As a result of various investigations on related topics, it has been found that there is no clear reason for this problem. However, many research teams have found that various experiments have found many likely causes. And one of them is about our brain and our experiences.

To clarify this, let’s first look at our brain. When we sleep, all the functions of our body seem to temporarily relax, but that is far from the truth. When we sleep, our brains do something very important.

A lot of neurons in the human brain that are connected to each other by synapses and are stored in pieces of information as memory in the circuits of our nerves.


In fact, according to a team at the University of Wisconsin, USA, the synapses in our brain continue to grow as we receive information while we are awake, creating complex circuits with other neurons. In other words, the brain communicates information and accumulates memory in this way.

Awakening brain
Source: Sensusport

However, this cannot be repeated indefinitely because there is a limit to the amount of information that the brain’s synapses can accept and the amount of work they can process. So our brain needs a concise summary or summarization of all the information the synapses have received, which is what the brain does while we are asleep.

Trouble sleeping
Source: Tenor

This sleep process is called REM (Rapid Eye Movement). In REM sleep, the right brain becomes active and processes the necessary work. The left brain, on the other hand, does something different and that’s what the topic is about today.

REM sleep is described in five stages. Stage 1,2,3 and 4 has been categorised as Non-REM. Meanwhile, stage 5 is for REM. Stage 1 and 2 are called shallow sleep, and Stage 3 and 4 are called deep sleep. The 5th stage of sleep is when you enter REM. You usually enter REM after 90 minutes of sleep and this is when you start dreaming.

Rapid eye movement

The current journal Biology tells us that one half of our brain, specifically the left hemisphere, sleeps less or is more active than the right brain, this is what they call the first night effect (FNE).

FNE is what happens when you change your bedtime routine or when you go to bed for the first time in a different environment. It is a natural instinct of the body to react to danger when you are in a different environment.

FNE is associated with a surveillance system in one brain hemisphere during NREM sleep, which manifests as interhemispheric asymmetry in sleep depth in the default-mode network (DMN) and increased vigilance toward monitoring external stimuli.

The present study investigated whether a similar surveillance system is exhibited during rapid eye movement (REM) sleep. The impacts of the FNE could be different between the phasic period, in which eyes move rapidly.

For the tonic period, in which eye movement ceases in REM sleep. Without the FNE, vigilance to external stimuli is generally reduced during the phasic period but not the tonic period. This surveillance system may be useful for protecting vulnerable sleepers from abnormal events in unfamiliar environments.


The reason why the left brain is awake in this strange situation is not yet clearly explained, but many researchers explain this in connection with animal instincts. Uncertainty increases in unfamiliar environments, so staying awake as much as possible favors survival, so our bodies do it instinctively.

First night effect

In fact, some marine mammals have a hemisphere sleep behavior in which only half of the brain sleeps. I’m talking about dolphins.  Being one of those mammals that live in water, Dolphins will rise to the surface for several times in an hour to breathe, which is quite troublesome when sleeping.

If a dolphin sleeps like a human, which is unconscious sleep, the probability for Dolphins to die due to lack of oxygen are high. Since it’s very likely that they’ll sink and fall into water. This is why they sleep with one eye open in the ocean.

To prevent them from drowning and being attacked, so instinctively half of their brain is awake. And for similar reasons, the left brain is activated in unfamiliar environments.

Half brain
Source: Giphy

Interestingly, people who sleep in unfamiliar surroundings, such as those who work abroad or travel, are more likely to sleep in unfamiliar surroundings. This is because the left brain isn’t very active since the brain has accepted that sleeping in an unfamiliar environment is a normal thing and not a threat.



  1. Research Gate: Night Watch in One Brain Hemisphere during Sleep Associated with the First Night Effect in Humans
  2. Medical News Today: What is REM
  3. Medical News Today: Why Do We Sleep Badly During First Night at the New Place
  4. Britannica Encyclopedia: Science Synapse
  5. ScienceDirect: The first night effect during polysomnography, and patients’ estimates of sleep quality
  6. You Ask We Answer: Why Do Dolphins Sleep With One Eye Closed



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