A new study has challenged the theory that sleep strengthens brain connections, while revealing that it is important because it weakens the connections among brain cells to save energy, avoid cellular stress, and maintain the ability of neurons to respond selectively to stimuli.
The synaptic homeostasis hypothesis of sleep or 'SHY', which takes into account years of evidence from human and animal studies, was conducted by two leading sleep scientists from the University of Wisconsin School of Medicine and Public Health.
Dr. Giulio Tononi, of the UW Center for Sleep and Consciousness, said during wake, learning strengthens the synaptic connections throughout the brain, increasing the need for energy and saturating the brain with new information.
Sleep allows the brain to reset, helping integrate, newly learned material with consolidated memories, so the brain can begin anew the next day.
Tononi and his co-author Dr. Chiara Cirelli conducted the laboratory studies sleep and consciousness in animals ranging from fruit flies to humans; SHY takes into account evidence from molecular, electrophysiological and behavioral studies, as well as from computer simulations.
Tononi said sleep helps the brain renormalize synaptic strength based on a comprehensive sampling of its overall knowledge of the environment, rather than being biased by the particular inputs of a particular waking day.
The study was published in the journal Neuron.