Sleep is a highly active brain process and is required for healthy brain function, said Christoph Nissen, a psychiatrist at the University of Freiburg.
Nissen’s study found that the loss of a single night’s sleep is enough to block the brain’s natural reset mechanism.
Moreover, his research showed for the first time that sleep resets the steady build-up of connectivity in the brain that occurs while we are awake. The process seems to be very important for the brain to remember and learn.
When the brain has insufficient rest, neurons became over-connected and muddled with electrical activity. Therefore, new memories could not be properly laid down.
Nissen found that sleep allows the brain to calm its activity so memories can be “written down”.
However, a brain that's lacking sleep becomes noisy with electrical activity and weak at laying down memories.
The outcomes of sleep loss were clear in a memory test, with tired volunteers performing worse than those who had a good sleep.
Giulio Tononi, a professor of sleep medicine at the University of Wisconsin-Madison, added that sleep allows the brain to learn new things every day while preserving and consolidating the old memories.
“Learning and memory require synaptic activity, which is very energetically expensive and prone to saturation,” he said.
“Sleep allows the brain to renormalise this synaptic activity after it increases in the waking day.”
Meanwhile, another study found that getting some sleep in between study sessions can make it easier to recall what you studied and relearn what you've forgotten - even six months later.
"Our results suggest that interleaving sleep between practice sessions leads to a twofold advantage, reducing the time spent relearning and ensuring a much better long-term retention than practice alone," said psychological scientist Stephanie Mazza of the University of Lyon.
"Previous research suggested that sleeping after learning is definitely a good strategy, but now we show that sleeping between two learning sessions greatly improves such a strategy."
According to Mazza, his research suggest that alternating study sessions with sleep might be an easy and effective way to remember information over longer periods of time.
Why do we spend about a third of our lives in a state of sleep?