One night without sleep tied to more brain connection markers
A PLOS Biology study using PET scans found higher synapse-marker signals after 28 hours awake, adding human evidence for sleep’s reset role.
By Tom Brennan · Health & Medicine Correspondent
2 min read
Researchers in Germany found that one night without sleep was linked to higher signals of a protein used as a marker for synapses in the human brain. The authors say the findings add human evidence for the idea that sleep helps restore balance after waking hours strengthen brain-cell connections.
The study, published in PLOS Biology, was led by David Elmenhorst of the Forschungszentrum Jülich Institute of Neuroscience and Medicine in North Rhine-Westphalia, Germany, with colleagues. The team used positron emission tomography, or PET, to study 40 participants, according to the Public Library of Science.
Half of the participants stayed awake through the night, the researchers reported. After 28 hours of continuous wakefulness, that sleep-deprived group showed higher measures of synaptic vesicle glycoprotein 2A, or SV2A, in several brain regions.
SV2A is used as a marker of synapses, the contact points through which brain cells communicate, according to the study. The authors reported higher SV2A measures in areas including the hippocampus, which is involved in memory, and the thalamus, which helps relay information in the brain.
The work tested a long-running idea known as the synaptic homeostasis hypothesis, the researchers said. Under that model, synapses strengthen while a person is awake, raising the brain’s energy demands and contributing to the accumulation of proteins; sleep is thought to reduce those connection levels and return the brain toward balance.
The authors said evidence for that model in humans has been limited, even though it has been studied in animals. Their PET approach offered a way to look for a human signal tied to synaptic density after sleep loss.
The study also examined what happened when sleep-deprived participants were allowed a two-hour nap. The researchers found that higher SV2A levels were associated with more slow-wave activity during sleep, a measure linked in the study to deep sleep and sleep pressure.
The authors cautioned that SV2A is an indirect measure of brain-cell connections. They also described the elevations as relatively small, meaning the results support the sleep-reset model without proving every step of the proposed mechanism.
The researchers said the pattern points to a biological link between the pressure to sleep and the buildup of neural connections during prolonged wakefulness. “During sleep deprivation, the brain remains awake longer and continues to process stimuli and information,” the authors said.
They added that after about 28.5 hours awake, the study found increased markers of synaptic density in multiple brain regions. In the authors’ view, that suggests sleep loss is accompanied by measurable changes in neural connections, beyond the familiar feeling of fatigue.
This story draws on original reporting from Medical Xpress.