Dopamine D1 receptors mediate desire. The D2 receptors mediate self-control. Addictive drugs downregulate the D2 receptors, inducing the craving and impulsivity of addiction.

The dopamine depletion that decreases mental energy can mean different alterations of the synaptic mechanisms that synthesize, store, release and eliminate dopamine.

Electrodes implanted in the reward pathway do not produce pleasure but craving.

The idea of mental energy makes intuitive sense and is present in mystical traditions. However, there is little evidence that pleasure and sex decrease it.