Mentally Hard Task Makes You Tired, Why?

Mentally hard tasks produce Glutamate  in brain’s prefrontal cortex

Glutamate molecule directly involved in Learning and memory of brain

If the Glutamate level is high it is toxic

Extreme tiredness is adaptation to reduce the accumulation of glutamate

glutamate regulation reduces the control exerted over decision-makingUp

high-demand cognitive work resulted in higher glutamate concentration and glutamate/glutamine diffusion in a cognitive control brain region (lateral prefrontal cortex [lPFC])

Feeling of tiredness

brain’s way of telling you to stop the working or thinking. so glutamate levels stop.

To restore Brains Function you need rest, sleep, breaks. "We are not machine"