The brain is much more active at night than during the day.
Logically, you would think that all the moving around, complicated calculations and tasks and general interaction we do on a daily basis during our working hours would take a lot more brain power than, say, lying in bed. Turns out, the opposite is true. When you turn off your brain turns on. Scientists don’t yet know why this is but you can thank the hard work of your brain while you sleep for all those pleasant dreams.
How the Brain Functions During Sleep
Research shows that the human brain is definitely impacted by sleep. While we are asleep, our brains are still busy at work. It is amazing how the brain is still completing tasks even while we are asleep. There is a neuronal system that controls the periods of sleep and wake and this system is located in the isodendritic core. It stretches from the medulla, throughout the brainstem and hypothalamus and finally reaching up into the basal forebrain (Izac, 2004). This core contains different neurons, which are important for wake and sleep. Both the sleep-active and wake-active neurons are intertwined (Izac, 2004).
Slow wave sleep has high EEG rhythms, which activates a large amount of neurons. These EEG waves are inactive during the wake and REM stages. The GABA sensitive neurons are found in the thalamic nucleus and are believed to be associated with slow wave sleep. Slow wave sleep is known for having a decrease in cellular firing in most areas of the brain, “compared to waking levels.” Slow wave sleep causes a reduction in activity in the thalamocortical system, with an increased amount of activity in the certain areas of the limbic system (Izac, 2004).
The sleep cycle is regulated by two pathways consisting of effector neurons. These neurons are designed to suppress or promote muscle atonia, rapid eye movements or EEG desynchronization found in REM sleep (Izac, 2004). Certain mechanisms found in the forebrain, may enhance REM sleep (Izac, 2004). According to Izac (2004), research has shown that monoaminergic neurons (containing norepinephrine and serotonin) may actually suppress REM sleep. In addition, research suggests that cholinergic neurons (containing acetylcholine) may possibly promote REM sleep (Izac, 2004).
According to Izac (2004), most brain areas display increased activity during sleep, when compared to slow-wave-sleep. REM sleep is very similar when compared to waking sleep. However, the limbic system is not active during REM sleep. During REM sleep, more individual neurons are fired throughout the brain’s motor systems. There is an increased amount of activity occurring in the cerebellum, cortex, and the pyramidal tract. Nevertheless, a majority of the motor neurons are “inhibited during REM” (Izac, 2004).