PsyPost reports:

A recent study has provided new insights into the complex role of sleep in brain function. Conducted on zebrafish, the research revealed that during the first half of a night’s sleep, the brain weakens the new connections between neurons formed while awake. However, this process does not continue into the second half of the night, leaving open questions about the latter stage’s purpose. Published in the journal Nature, the study supports the Synaptic Homeostasis Hypothesis, which suggests sleep serves as a reset for the brain.

The exact function of sleep has long puzzled scientists. While it is known that sleep is crucial for cognitive performance, its precise role at the neuronal level remains unclear. One prevailing theory is the Synaptic Homeostasis Hypothesis, which posits that sleep helps balance the strengthening and weakening of synapses (connections between neurons) that occur during waking hours. This balance is essential because continuous strengthening of synapses would be energetically unsustainable and could impede the formation of new connections needed for learning. The researchers aimed to test this hypothesis by observing the synaptic changes that occur during sleep in zebrafish.

To explore these changes, researchers used optically translucent zebrafish with genetically modified brains that allowed easy imaging of synapses. They monitored the fish over several sleep-wake cycles to observe how synaptic connections evolved. Specifically, they tracked the changes in synapse numbers and strengths across different phases of the day and night. [Continue reading…]