Ever woken up tired after full night's sleep? Neuroscientists study brain scans to find out why
A new study, published in Current Biology, looked at how our brain works during the time when we wake up. Scientists at the Netherlands Institute for Neuroscience tracked the brain activity of 20 people, recording more than 1,000 wake-ups, some natural, others triggered by an alarm.
'The surprise is how consistent [this pattern] was across every awakening and also how it related to the subjective measures,' Francesca Siclari, the study's senior author and a neuroscientist at the Institute, was quoted as saying by Nature.
Each person wore a special cap with 256 sensors that picked up brain signals every second. By watching how the brain 'turned on,' the researchers found that the way people woke up depended on which stage of sleep they were in.
When people were woken up during REM sleep– the stage when we usually dream, they were more likely to feel tired and slow. That's because their brain switched on in a certain order. First, the front part of the brain (which helps with thinking and decision-making) becomes active. Then, a slow wave of activity moves to the back of the brain, where we process what we see.
In contrast, people woken from non-REM sleep had a slightly different pattern. The brain wave started more in the middle and moved in the same direction but may have felt more natural.
This research could help doctors better understand why some people wake up feeling refreshed while others feel tired, even if they slept for the same amount of time. It might also help in studying sleep disorders or problems like feeling tired all the time.
'Knowing exactly how brain activity is characterized during a normal awakening [means] we can better compare it to these abnormal awakenings,' Siclari said. While more studies are needed, especially to see how other factors such as body movement affect sleep, this study shows that how we wake up matters just as much as how long we sleep.
(This article has been curated by Kaashvi Khubyani, who is an intern with The Indian Express)
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