Study: Lack of sleep increases brain cell connections

New research indicates that a lack of sleep leads to a measurable increase in connections between brain cells. The study, published in "PLOS," suggests that during wakefulness, the brain forms more and stronger synaptic connections, which consume more energy and lead to protein buildup.

Scientists from the Forschungszentrum Jülich Institute of Neuroscience and Medicine in Germany utilized positron emission tomography (PET) to measure SV2A, a marker for brain synapses. The study involved 40 participants, half of whom were deprived of sleep for one night. After approximately 28 hours of continuous wakefulness, the sleep-deprived group showed higher levels of SV2A in several brain regions, including the hippocampus, crucial for memory, and the thalamus, a key information relay center.

These findings support the synaptic homeostasis hypothesis, which posits that sleep is essential for restoring the brain's balance. The hypothesis suggests that sleep reduces the number of synaptic connections formed during wakefulness, thereby conserving energy and clearing accumulated proteins. While SV2A is an indicator and the observed increase was relatively small, the results align with this model.

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Sleep deprivation not only causes fatigue but is also accompanied by measurable changes in neuronal connections.

"During sleep deprivation, the brain remains in a waking state for longer and continues to process stimuli and information," the study's authors noted. "Our study shows that after about 28.5 hours of wakefulness, the synaptic density index increases in several brain areas. This suggests that sleep deprivation not only causes fatigue but is also accompanied by measurable changes in neuronal connections."

When the sleep-deprived participants were allowed a two-hour nap, higher SV2A levels correlated with increased slow-wave activity during sleep, a marker of deep sleep. This further reinforces the biological connection between the need for sleep and the accumulation of cellular connections.

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Our study shows that after about 28.5 hours of wakefulness, the synaptic density index increases in several brain areas.