Sleep deprivation majorly impacts the brain’s connectivity and function, according to a recent study published this February in NeuroImage. As well as affecting many important networks, sleep deprivation prevented normal changes to brain function between the morning and evening.
Sleep is an essential human state which is necessary for maintaining healthy function throughout the body. Therefore, lack of sleep has severe health-related consequences, with the brain being the most affected organ.
Lack of sleep can negatively affect memory, emotional processing and attentional capacities. For example, sleep deprivation has been shown to disrupt functional connectivity in hippocampal circuits (important for memory), and between the amygdala (important for emotion regulation) and executive control regions (involved in processes such as attention, planning, reasoning and cognitive flexibility). The emotional effects of sleep deprivation can be to both alter response patterns to negative things but also enhance reactivity toward positive things.
The study, led by Tobias Kaufmann of University of Oslo, involved 60 young men who completed three resting state functional magnetic resonance imaging (fMRI) scans – this is used to evaluate connectivity between brain regions when a person is not performing a task.
They were scanned in the morning and evening of the same day – this was to account for changes from morning to evening in normal brain function (diurnal variability). 41 men then underwent total sleep deprivation, whereas the remainder had another night of regular sleep, before they were scanned again the following morning. Finally, behavioural assessments of vigilance and visual attention were assessed.
The findings revealed that sleep deprivation strongly altered the connectivity of many resting-state networks; most clearly affected were networks important for memory (hippocampal networks) and attention (dorsal attention networks), as well as the default mode network (an interconnected set of brain regions active when a person is daydreaming or their mind is wandering).
In fact, they identified a set of 17 brain network connections showing altered brain connectivity. Furthermore, correlation analysis suggested that morning-to-evening connectivity changes returned the next day in the group that had slept the night, but not in the sleep-deprivation group.
The study emphasizes the major impact of sleep deprivation on the brain’s connectivity and function, as well as providing evidence that normal morning-to-evening connectivity changes do not occur after a night without sleep.