The Reason Sleep Is Disturbed On First Night In Unfamiliar Surroundings

Study helps explain the ‘first night effect’.

It can be hard to sleep on the first night in a new place: such as on holiday or when visiting friends.


Dr Yuka Sasaki, author of a new study, said:


“In Japan they say, ‘if you change your pillow, you can’t sleep.

You don’t sleep very well in a new place.

We all know about it.”

The reason could be down to the fact that one of the brain’s hemispheres stays more awake: alert for trouble.

For the research, scientists measured people’s brain activity on the first night in the sleep lab.

They focused on the part of the sleep cycle in which deep sleep occurs — sometimes called slow-wave sleep.

The sleepers were played irregular beeping sounds while they were asleep to examine the brain’s alertness.

The study’s authors conclude:


“The present study has demonstrated that when we are in a novel environment, inter-hemispheric asymmetry occurs in regional slow-wave activity, vigilance and responsiveness, as a night watch to protect ourselves.”


SOURCE:

http://www.spring.org.uk/2016/04/first-night-effect-sleep-disturbed.php(accessed 26.4.16)

The study was published in the journal Current Biology (Tamaki et al., 2016).

The science of sleep

We spend a third of our lives doing it.

Napoleon, Florence Nightingale and Margaret Thatcher got by on four hours a night.

Thomas Edison claimed it was waste of time.

Why do we sleep?

So why do we sleep? This is a question that has baffled scientists for centuries and the answer is, no one is really sure. Some believe that sleep gives the body a chance to recuperate from the day's activities but in reality, the amount of energy saved by sleeping for even eight hours is miniscule - about 50 kCal, the same amount of energy in a piece of toast.

We have to sleep because it is essential to maintaining normal levels of cognitive skills such as speech, memory, innovative and flexible thinking. In other words, sleep plays a significant role in brain development.

What would happen if we didn't sleep?

A good way to understand the role of sleep is to look at what would happen if we didn't sleep. Lack of sleep has serious effects on our brain's ability to function. If you've ever pulled an all-nighter, you'll be familiar with the following after-effects: grumpiness, grogginess, irritability and forgetfulness. After just one night without sleep, concentration becomes more difficult and attention span shortens considerably.

With continued lack of sufficient sleep, the part of the brain that controls language, memory, planning and sense of time is severely affected, practically shutting down. In fact, 17 hours of sustained wakefulness leads to a decrease in performance equivalent to a blood alcohol level of 0.05% (two glasses of wine). This is the legal drink driving limit in the UK.

Research also shows that sleep-deprived individuals often have difficulty in responding to rapidly changing situations and making rational judgements. In real life situations, the consequences are grave and lack of sleep is said to have been be a contributory factor to a number of international disasters such as Exxon Valdez, Chernobyl, Three Mile Island and the Challenger shuttle explosion.

Sleep deprivation not only has a major impact on cognitive functioning but also on emotional and physical health. Disorders such as sleep apnoea which result in excessive daytime sleepiness have been linked to stress and high blood pressure. Research has also suggested that sleep loss may increase the risk of obesity because chemicals and hormones that play a key role in controlling appetite and weight gain are released during sleep.

What happens when we sleep?

What happens every time we get a bit of shut eye? Sleep occurs in a recurring cycle of 90 to 110 minutes and is divided into two categories: non-REM (which is further split into four stages) and REM sleep.

Non-REM sleep

Stage one: Light Sleep

During the first stage of sleep, we're half awake and half asleep. Our muscle activity slows down and slight twitching may occur. This is a period of light sleep, meaning we can be awakened easily at this stage.

Stage two: True Sleep

Within ten minutes of light sleep, we enter stage two, which lasts around 20 minutes. The breathing pattern and heart rate start to slow down. This period accounts for the largest part of human sleep.

Stages three and four: Deep Sleep

During stage three, the brain begins to produce delta waves, a type of wave that is large (high amplitude) and slow (low frequency). Breathing and heart rate are at their lowest levels.

Stage four is characterised by rhythmic breathing and limited muscle activity. If we are awakened during deep sleep we do not adjust immediately and often feel groggy and disoriented for several minutes after waking up. Some children experience bed-wetting, night terrors, or sleepwalking during this stage.

REM sleep

The first rapid eye movement (REM) period usually begins about 70 to 90 minutes after we fall asleep. We have around three to five REM episodes a night.

Although we are not conscious, the brain is very active - often more so than when we are awake. This is the period when most dreams occur. Our eyes dart around (hence the name), our breathing rate and blood pressure rise. However, our bodies are effectively paralysed, said to be nature's way of preventing us from acting out our dreams.

After REM sleep, the whole cycle begins again.

How much sleep is required?

There is no set amount of time that everyone needs to sleep, since it varies from person to person. Results from the sleep profiler indicate that people like to sleep anywhere between 5 and 11 hours, with the average being 7.75 hours.

Jim Horne from Loughborough University's Sleep Research Centre has a simple answer though: "The amount of sleep we require is what we need not to be sleepy in the daytime."


Even animals require varied amounts of sleep:
Species Average total sleep time per day
Python 18 hrs
Tiger 15.8 hrs
Cat 12.1 hrs
Chimpanzee 9.7 hrs
Sheep 3.8 hrs
African elephant 3.3 hrs
Giraffe 1.9 hr


The current world record for the longest period without sleep is 11 days, set by Randy Gardner in 1965. Four days into the research, he began hallucinating. This was followed by a delusion where he thought he was a famous footballer. Surprisingly, Randy was actually functioning quite well at the end of his research and he could still beat the scientist at pinball.




SOURCE:


BBC Sciece: Human body & Mind

http://www.bbc.co.uk/science/humanbody/sleep/articles/whatissleep.shtml

Why teens should have their music and sports lessons in the evening?

While you sleep your brain learns. Research with rats has shown how they rehearse maze-routes in their brains whilst they're dozing. And human research has demonstrated that learned material is better recalled after a sound sleep as opposed to a disturbed night. But what hasn't been looked at before now is the optimum time to leave between learning and sleeping.

A team led by Johannes Holz has done just that, finding that "procedural learning" (practice at the kind of skill that you do, rather than talk about) is more effective right before sleep. Learning factual material, by contrast, (dependent on "declarative memory"), was found to be more effective when done in the afternoon, seven and a half hours before sleep, although the evidence for this was less convincing and should be treated with caution.

The researchers recruited 50 teenage girls (aged 16-17) to learn a series of word pairs and a finger-tapping task, either at 3pm in the afternoon or 9pm at night. The performance level of the afternoon and night groups was equivalent at the end of these initial learning tasks.

With the tapping task, it was the girls who learned right before sleep who showed the greatest gains in performance when they were re-tested after 24 hours and again 7 days later. Holz and his colleagues can't be sure why procedural learning is more effective just before sleep, but they think it probably has to do with the effect of sleep on protein synthesis and gene expression.

In contrast to the tapping task, performance on the word pairs after 24 hours was better in the afternoon-learning group. At the 7 day word-pairs test there was no difference in afternoon or evening learners. The fact that declarative learning was more effective in the afternoon suggests that this type of hippocampus-dependent memory has a different time course from procedural learning.

The findings, though preliminary, have obvious practical implications. "We propose that declarative memories, such as vocabulary words, should be studied in the afternoon and motor skills, like playing soccer or piano, should be trained in the late evening," the researchers said. "Most parents among us would have preferred the opposite results."
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Source:

 

PSYCHOLOGY DIGEST : http://www.researchdigest.org.uk/

Holz J, Piosczyk H, Landmann N, Feige B, Spiegelhalder K, Riemann D, Nissen C, and Voderholzer U (2012). The Timing of Learning before Night-Time Sleep Differentially Affects Declarative and Procedural Long-Term Memory Consolidation in Adolescents. PloS one, 7 (7) PMID: http://www.ncbi.nlm.nih.gov/pubmed/22808287