Little sleep is harmful, we know. More and more studies are pointing out the psychological and physical risks of sleeping little or badly. In fact, we now know that sleep is essential to reduce the emotional impact of the experiences we experience during the day, it is also essential to memorize and even allow the brain to get rid of the waste substances of its metabolism. However, since every coin always has two sides, sleeping too much is also bad and can be very harmful.
Sleeping a lot affects our cognitive abilities
One major sleep study concluded that the ideal is to find a balance. After collecting data from more than 10.000 people around the world, Western University researchers found that sleeping too much hurts.
Participants filled out questionnaires about their sleep habits and underwent a series of tests aimed at assessing their cognitive abilities. The researchers cross-referenced all kinds of data, from age and educational level to the drugs used by the participants. So they found that, regardless of these details, there was a common factor: the longer they slept, the greater the deterioration in cognitive function.
Both reasoning and verbal fluency depended on the duration of sleep. Intellectual performance was equally negatively affected in people who slept little as in those who slept a lot. The ideal balance point was identified between 7 and 8 hours of sleep.
In fact, this isn't the first study to suggest a relationship between sleep duration and decline in cognitive function. Other research conducted at Brigham & Women Hospital in Boston collected information on more than 15.000 women over the age of 70.
All of them underwent cognitive tests every two years during the six years of study. Their sleep habits were also analyzed. The researchers found that sleep hours correlated with cognitive decline over time:
- Women who slept five hours a day or less during the night had lower cognitive performance than those who slept seven hours a day.
- Women who slept more than nine hours had lower cognitive performance than those who slept seven hours a day.
Curiously, both women who slept little and those who slept a lot were two years older than those who slept the necessary. This meant that their brains had aged faster.
Why Does Sleeping Too Much Negatively Affect Our Brain?
The effects of excess sleep on the brain have not yet been fully studied. However, sleep is known to greatly affect our circadian rhythm: a 24-hour cycle driven by our biological clocks that generates physical, mental and behavioral changes.
When we sleep more than usual, we break our circadian rhythm. In fact, the feeling of lethargy, tiredness and drowsiness comes from a sleep cycle that has lost its tune, it's like a continuous jet lag. As a result, people who sleep too much will begin to experience a variety of side effects that are the result of the body's struggle to synchronize.
Excess sleep can also affect the production and reception of some neurotransmitters in the brain, particularly serotonin. This is why it is no coincidence that many people who sleep a lot complain of headaches during the day or even nausea.