Why we sleep and why we need sleep are questions that have consistently puzzled scientists. However, novel work from researchers at the University of Wisconsin School of Medicine and Public Health have tested their synaptic homeostasis hypothesis (SHY) for why animals need sleep.

SHY theory describes a need for sleep

This four-year study by Luisa de Vivo and her colleagues, published in Science, supported the SHY theory. The SHY theory describes changes in synapses during waking and sleeping hours. Synapses are the junctions between two neurons, the larger the synapse, the stronger these two neurons can communicate – this ease of communication is how animals learn skills and make memories. Yet in order for brains to be pliable and learn new things, the synapses must shrink so these neural pathways can be activated again. SHY theory suggests that sleep allows these synapses to shrink.

According to SHY theory, sleep provides the perfect environment for the shrinking of synapses, allowing the brain to learn new things following day. The lack of stimulation while sleeping results in reduced activity between neurons, and therefore the distance between the neurons grows smaller allowing them to be activated with a weaker stimulation. This phenomenon allows brains to make new neural connections the following day, thereby allowing new memories to form and more efficient learning.