Mental energy may be understood as the ability or willingness to engage in cognitive work. [1]
It is distinct from physical energy, [1] and has mood, cognition, and motivation domains. [2] [3] [4] [5] Concepts closely related to mental energy include vigor and fatigue. [1]
Mental energy is not well-defined, and the scientific literature on mental energy is quite limited. [1] The philosopher and psychologist Karl F. Stifter wrote a dissertation on the "Philosophy of Mental Energy". [6] In the Austrian Broadcasting Corporation's TV show "Vera", Stifter lifted 1000 kg with a lifting belt over his sacrum to prove that drastic increases in muscle strength can be achieved after special mental training. [7] A variety of measures for assessing aspects of mental energy exist. [1]
Many people complain of low mental energy, which can interfere with work and daily activities. [1] Low mental energy and fatigue are major public health concerns. [1] People may pursue remedies or treatment for low mental energy. [1] Seeking to improve mental energy is a common reason that people take dietary supplements. [8]
Many different neurotransmitters have been theoretically implicated in the control of mental energy. [8] This has often been based on the effects of drugs acting on these neurotransmitters. [8] These neurotransmitters include dopamine, norepinephrine, orexin, serotonin, histamine, acetylcholine, adenosine, and glutamate. [8] Hormones, including glucocorticoids like cortisol, as well as cytokines, have also been found to regulate mental energy. [9] [10] [11] [12]
Mental energy can be affected by factors such as drugs, sleep, and disease. [1]
Drugs that may increase mental energy include caffeine, modafinil, psychostimulants like amphetamines and methylphenidate, and corticosteroids like hydrocortisone and dexamethasone. [1] [8] [9]
Drugs that may decrease mental energy include sedatives and hypnotics like antihistamines, benzodiazepines, and melatonin, as well as dopamine receptor antagonists like antipsychotics. [1] [13]
There are many marketing claims of foods, beverages, and dietary supplements improving mental energy, but data to substantiate such claims are limited or absent. [5] [8] [14]
Sleep deprivation may decrease mental energy in an exposure-dependent manner. [1]
Various disease states, such as cardiac disease, cancer, stroke, HIV/AIDS, multiple sclerosis, Parkinson's disease, and certain mental health conditions like depression, may be associated with decreased mental energy. [1] Chronic fatigue syndrome is characterized by a lack of the energy needed for the basic activities of daily life. [1]