As a species, we can all pretty much agree that we’re keen on survival. Although our instincts have dulled due to centuries of increased comfort, millennia of evolution caused some of them to remain, although some are in contrast with the society in which we live. It’s a tough situation.
Most of these instinct relate to survival, either that of the individual or that of the species. And since sleep is such an important part of our lives, you can bet that we still have some vestige instincts related to it. For example, light is an indicator of wakefulness, so a team of Norwegian scientists showed that sleep quality is affected by reading a tablet.
Light and sleep
According to the study performed by the Norwegian team, people who read from their tablets for half an hour before going to sleep felt less sleepy as they did so and had a different electrical activity in the brain, indicative of little restfulness, as opposed to those reading from a book.
Still, it took similar times to fall asleep and the participants were awake for similar amounts of time. Even though the researchers found it surprising that the tablet didn’t cause the participants to take longer to fall asleep, a half an hour delay was noticed in the apparition of restorative slow waves.
The reason behind this is that our ancestors evolved to know that light meant they had to get things done. With no sources of artificial illumination, any strong light meant that the sun was up, so they had to start their day. And this trait evolved over tens of thousands of years hasn’t yet been completely removed by a few years of comfort.
Led by Janne Gronli from the University of Bergen in Norway, the study had quite a small sample – sixteen non-smokers aged 22 to 33, with no history of psychiatric, medical or sleep disorders. They were all familiar with tablets, and for a week before the study they followed a regular sleep schedule and slept for however much they needed.
The study lasted for three nights, and polysomnographic recordings were taken of the participants in each of the three. Data collected was related to sleep efficiency, total sleep time, time spent in each stage of sleep and other sleep quality-related data.
For the first night, the subjects slept regularly so that a baseline could be recorded. The second night saw them reading from a tablet for half an hour before going to sleep, and the third one saw them reading a book.
A light meter measured the light at eye level during each night and revealed the tablet producing twice the amounts of light as the book, along with a high level of blue light. As expected participants were sleepier when reading the book, and slow wave activity, responsible for deep sleep, was delayed and slowed down.
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