Brain Fog is Real: How Missing Sleep Decimates Your Reaction Time and Focus
Brain fog is real. The solution is not more coffee.
In a controlled clinical trial evaluating the acute effects of total sleep deprivation on cognitive performance, researchers tested participants' mental processing speeds using P300 event-related brain potentials and visual reaction time tasks (Ren, 2025). The study revealed that just one night of total sleep loss significantly delayed brain signal transmission speed by nearly a full 10% decrease. Sounds small, but tell a neurologist that and they’d freak out. This of course caused a noticeable spike in reaction times across cognitive tasks. Missing a single night's rest directly degrades speed, accuracy, and sustained attention, effectively putting your brain's processing capacity into low-power mode.
Read the study on PMC
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