Experiments exploring the effects of missing a night’s sleep on the human brain have found indications that a sleepless night actually increases connections between brain cells instead of impeding growth. However, the lack of sleep could also create brain “fatigue” and pressure, resulting in burnout.
The Forschungszentrum Jülich Institute of Neuroscience and Medicine team behind the discovery said that their findings might support the idea that sleep plays an important role in restoring the brain’s cellular balance.
Missing a Night’s Sleep Could Disrupt Cellular Balance
In a statement announcing the surprising discovery, study leader David Elmenhorst and colleagues note that scientists still are not in complete consensus about why humans and other animals need sleep. One proposal involves restoring synaptic connections between brain cells during certain stages of sleep, helping the brain maintain a form of cellular ‘homeostasis.’
For example, previous research has shown that synaptic connectivity increases during wakefulness. This increased activity also increases energy consumption, potentially resulting in problematic protein buildup. Conversely, scientists suspect that sleep helps restore baseline synaptic connections and protein levels, thereby maintaining a healthy cellular balance.
“Sleep is essential for synaptic homeostasis, a proposed mechanism whereby wakefulness leads to synaptic potentiation, and sleep facilitates synaptic down-selection,” the research team explains in a recently published study.
Although previous studies suggest that missing a night’s sleep could disrupt this balance, the team notes that there is very little experimental data to support these conclusions.
Study Reveals Elevated Synaptic Activity After 28 Hours Awake
To explore the role of sleep in cellular homeostasis in the human brain, the researchers used an advanced brain-scanning technology called positron emission tomography (PET). According to the team’s statement, this tool can scan the human brain for signs of synaptic vesicle glycoprotein 2A (SV2A), which they describe as a “marker” of brain synapses.
The team started by enlisting 40 study volunteers. Next, each volunteer was given a PET scan to establish baseline marker levels. After their first scan, 20 of the volunteers were told to get a normal night’s sleep. According to the study authors, the second half were assigned to “the sleep deprivation condition,” where they were told to miss a night’s sleep.
The next day, the team used the PET scan to search for telltale brain synapse markers. As hoped, the scans revealed a distinct difference between the two groups. Where the normal sleep group’s levels were within expected ranges, the synapse markers of the volunteers who had missed a night’s sleep were elevated.
A closer analysis found that once people passed 28 hours of continued wakefulness, their SV2A markers were higher “in several brain regions.” Notably, these increased markers were detected in the hippocampus, which plays an important role in memory, and in the thalamus, which is critical for information relay within the brain.
“Sleep deprivation led to significant increases in synaptic vesicle glycoprotein 2A binding in multiple brain regions, including the thalamus (+4.6%), hippocampus (+5.6%), and parietal cortex (+3.2%), whereas no changes were observed in controls,” the study authors write.
Sleep Deprivation Causes Fatigue and CHanges Neural COnnections
When discussing the study’s limitations, the authors note that the SV2A marker used is a “proxy” for connections between brain cells, not a direct measure. They also note that the observed changes after a missed night’s sleep “were relatively small.” Still, they add, the results in several regions across several study participants “suggest a biological connection between the need for sleep and the buildup of cell connections.”
“During sleep deprivation, the brain remains awake longer and continues to process stimuli and information,” they write. “Our study shows that after approximately 28.5 hours of wakefulness, a marker for synaptic density increases in several brain regions. This suggests that sleep deprivation not only causes fatigue but is also accompanied by measurable changes in neural connections.”
The study “Sleep deprivation increases levels of the synaptic density marker SV2A in the human brain” was published in PLOS Biology.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.