11. Roelands B, de Koning J, Foster C, Hettinga F, Meeusen R. Neurophysiological determinants of theoretical concepts and mechanisms involved in pacing. Sports Med. 2013;43:301–11. https://pubmed.ncbi.nlm.nih.gov/23456493/
12. Rattray B, Argus C, Martin K, Northey J, Driller M. Is it time to turn our attention toward central mechanisms for post-exertional recovery strategies and performance? Front Physiol. 2015;6:79. https://www.frontiersin.org/ articles/10.3389/fphys.2015.00079/full
13. Cordeiro LMS, Rabelo PCR, Moraes MM, Teixeira-Coelho F, Coimbra CC, Wanner SP, et al. Physical exercise-induced fatigue: the role of serotonergic and dopaminergic systems. Braz J Med Biol Res. 2017;50:e6432. https:// pubmed.ncbi.nlm.nih.gov/29069229/
14. Noakes TD. Fatigue is a brain-derived emotion that regulates the exercise behavior to ensure the protection of whole body homeostasis. Front Physiol. 2012;3:82. https://pubmed.ncbi.nlm.nih.gov/22514538/
15. Taylor JL, Amann M, Duchateau J, Meeusen R, Rice CL. Neural contributions to muscle fatigue: from the brain to the muscle and back again. Med Sci Sports Exerc. 2016;48:2294–2306. https://pubmed.ncbi.nlm.nih.gov/ 27003703/
16. Kent-Braun JA, Sharma KR, Weiner MW, Massie B, Miller RG. Central basis of muscle fatigue in chronic fatigue syndrome. Neurology. 1993;43:125–31. https://pubmed.ncbi.nlm.nih.gov/8423875/
17. Schillings ML, Kalkman JS, van der Werf SP, van Engelen BGM, Bleijenberg G, Zwarts MJ. Diminished central activation during maximal voluntary contraction in chronic fatigue syndrome. Clin Neurophysiol. 2004;115:2518–24. https://pubmed.ncbi.nlm.nih.gov/15465441/
18. Robinson RL, Stephenson JJ, Dennehy EB, Grabner M, Faries D, Palli SR, et al. The importance of unresolved fatigue in depression: costs and comorbidities. Psychosomatics. 2015;56:274–85. https://pubmed.ncbi.nlm.nih.gov/ 25596022/
19. Barroso J, Bengtson AM, Gaynes BN, McGuinness T, Quinlivan EB, Ogle M, et al. Improvements in depression and changes in fatigue: results from the SLAM DUNC depression treatment trial. AIDS Behav. 2016;20:235–42. https://www.researchgate.net/publication/283493669_Improvements_in _Depression_and_Changes_in_Fatigue_Results_from_the_SLAM_DUNC _Depression_Treatment_Trial
20. Madill PV. Chronic fatigue syndrome and the cholinergic hypothesis (letter). JAMA. 2004;292:2723. https://jamanetwork.com/journals/jama/ article-abstract/199941
21. Spence VA, Khan F, Kennedy G, Abbot NC, Belch JJF. Acetylcholine mediated vasodilatation in the microcirculation of patients with chronic fatigue syndrome. Prostaglandins Leukot Essent Fatty Acids. 2004;70:403–7. https:// pubmed.ncbi.nlm.nih.gov/15041034/
22. Sam C, Bordoni B. Physiology, Acetylcholine. StatPearls. (Treasure Island, FL: StatPearls Publishing, 2020). https://www.ncbi.nlm.nih.gov/books/ NBK557825/
23. Bartus RT, Dean RL 3rd, Beer B, Lippa AS. The cholinergic hypothesis of geriatric memory dysfunction. Science. 1982;217:408–14. https://pubmed.ncbi.nlm.nih.gov/7046051/
24. Craig LA, Hong NS, McDonald RJ. Revisiting the cholinergic hypothesis in the development of Alzheimer’s disease. Neurosci Biobehav Rev. 2011;35:1397–409. https://pubmed.ncbi.nlm.nih.gov/21392524/
25. Wise RA, Robble MA. Dopamine and addiction. Annu Rev Psychol. 2020;71:79–106. https://www.annualreviews.org/doi/abs/10.1146/ annurev-psych-010418-103337
26. Dobryakova E, Genova HM, DeLuca J, Wylie GR. The dopamine imbalance hypothesis of fatigue in multiple sclerosis and other neurological disorders. Front Neurol. 2015;6:52. https://www.frontiersin.org/articles/10.3389/ fneur.2015.00052/full
27. Ledinek AH, Sajko MC, Rot U. Evaluating the effects of amantadin, modafinil and acetyl-L-carnitine on fatigue in multiple sclerosis-result of a pilot randomized, blind study. Clin Neurol Neurosurg. 2013;115 Suppl 1:S86–89. https://pubmed.ncbi.nlm.nih.gov/24321164/
28. Berger M, Gray JA, Roth BL. The expanded biology of serotonin. Annu Rev Med. 2009;60:355–66. https://pubmed.ncbi.nlm.nih.gov/19630576/
29. Ibid.
30. Aghajanian GK, Marek GJ. Serotonin and hallucinogens. Neuropsychopharmacology. 1999;21:16S–23S. https://pubmed.ncbi.nlm.nih.gov/10432484/
31. Lin S-H, Lee L-T, Yang YK. Serotonin and mental disorders: a concise review on molecular neuroimaging evidence. Clin Psychopharmacol Neurosci. 2014;12:196–202. https://pubmed.ncbi.nlm.nih.gov/25598822/
32. Yohn CN, Gergues MM, Samuels BA. The role of 5-HT receptors in depression. Mol Brain. 2017;10:28. https://pubmed.ncbi.nlm.nih.gov/ 28646910/
33. Cowen PJ, Browning M. What has serotonin to do with depression? World Psychiatry. 2015;14:158–60. https://www.ncbi.nlm.nih.gov/pmc/articles/ PMC4471964/
34. Yamamoto S, Ouchi Y, Onoe H, Yoshikawa E, Tsukada H, Takahashi H, et al. Reduction of serotonin transporters of patients with chronic fatigue syndrome. Neuroreport. 2004;15:2571–74. https://pubmed.ncbi.nlm.nih.gov/15570154/
35. Hesse S, Moeller F, Petroff D, Lobsien D, Luthardt J, Regenthal R, et al. Altered serotonin transporter availability in patients with multiple sclerosis. Eur J Nucl Med Mol Imaging. 2014;41:827–35. https://link.springer.com/ article/10.1007/s00259-013-2636-z
36. The GKH, Verkes RJ, Fekkes D, Bleijenberg G, van der Meer JWM, Buitelaar JK. Tryptophan depletion in chronic fatigue syndrome, a pilot cross-over study. BMC Res Notes. 2014;7:650. https://www.mendeley.com/catalogue/ a6c5f395-3633-3eb4-b1a3-1007b7206cfa/
37. Prober DA. Discovery of hypocretin/orexin ushers in a new era of sleep research. Trends Neurosci. 2018;41:70–72. https://pubmed.ncbi.nlm.nih.gov/29405929/
38. Mahlios J, De la Herrán-Arita AK, Mignot E. The autoimmune basis of narcolepsy. Curr Opin Neurobiol. 2013;23:767–73. https://pubmed.ncbi.nlm.nih.gov/23725858/
39. Coleman PJ, Gotter AL, Herring WJ, Winrow CJ, Renger JJ. The discovery of suvorexant, the first orexin receptor drug for insomnia. Annu Rev Pharmacol Toxicol. 2017;57:509–33. https://pubmed.ncbi.nlm.nih.gov/27860547/40. Chieffi S, Carotenuto M, Monda V, Valenzano A, Villano I, Precenzano F, et al. Orexin system: the key for a healthy life. Front Physiol. 2017;8:357. https://pubmed.ncbi.nlm.nih.gov/28620314/
41. Hao Y-Y, Yuan H-W, Fang P-H, Zhang Y, Liao Y-X, Shen C, et al. Plasma orexin-A level associated with physical activity in obese people. Eat Weight Disord. 2017;22:69–77. https://pubmed.ncbi.nlm.nih.gov/27038345/
42. Ibid.
43. Kotz CM, Teske JA, Levine JA, Wang C. Feeding and activity induced by orexin A in the lateral hypothalamus in rats. Regul Pept. 2002;104:27–32. https://pubmed.ncbi.nlm.nih.gov/11830273/
44. Gottesmann C. GABA mechanisms and sleep. Neuroscience. 2002;111:231–39. https://pubmed.ncbi.nlm.nih.gov/11983310/
45. Abdou AM, Higashiguchi S, Horie K, Kim M, Hatta H, Yokogoshi H. Relaxation and immunity enhancement effects of gamma-aminobutyric acid (GABA) administration in humans. Biofactors. 2006;26:201–8. https:// pubmed.ncbi.nlm.nih.gov/16971751/
46. Möhler H. Role of GABAA receptors in cognition. Biochem Soc Trans. 2009;37:1328–33. https://pubmed.ncbi.nlm.nih.gov/19909270/
47. Losi G, Mariotti L, Carmignoto G. GABAergic interneuron to astrocyte signalling: a neglected form of cell communication in the brain. Philos Trans R Soc Lond B Biol Sci. 2014;369:20130609. https://www.ncbi.nlm.nih.gov/ pmc/articles/PMC4173294/
48. Schmidt-Wilcke T, Fuchs E, Funke K, Vlachos A, Müller-Dahlhaus F, Puts NAJ, et al. GABA-from Inhibition to cognition: emerging concepts. Neuroscientist. 2018;24:501–15. https://pubmed.ncbi.nlm.nih.gov/29283020/
49. Sumner P, Edden RAE, Bompas A, Evans CJ, Singh KD. More GABA, less distraction: a neurochemical predictor of motor decision speed. Nat Neurosci. 2010;13:825–27. https://pubmed.ncbi.nlm.nih.gov/20512136/
50. Steenbergen L, Sellaro R, Stock A-K, Beste C, Colzato LS. γ-Aminobutyric acid (GABA) administration improves action selection processes: a randomised controlled trial. Sci Rep. 2015;5:12770. https://pubmed.ncbi.nlm.nih.gov/ 26227783/
51. Leonte A, Colzato LS, Steenbergen L, Hommel B, Akyürek EG. Supplementation of gamma-aminobutyric acid (GABA) affects temporal, but not spatial visual attention. Brain Cogn. 2018;120:8–16. https://pubmed.ncbi.nlm.nih.gov/29222993/
52. Cao G, Edden RAE, Gao F, Li H, Gong T, Chen W, et al. Reduced GABA levels correlate with cognitive impairment in patients with relapsing-remitting multiple sclerosis. Eur Radiol. 2018;28:1140–48. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5812783/
53. Sandberg K, Blicher JU, Dong MY, Rees G, Near J, Kanai R. Occipital GABA correlates with cognitive failures in daily life. Neuroimage. 2014;87:55–60. https://pubmed.ncbi.nlm.nih.gov/24188817/
54. Cook E, Hammett ST, Larsson J. GABA predicts visual intelligence. Neurosci Lett. 2016;632:50–54. https://pubmed.ncbi.nlm.nih.gov/27495012/
55. Wang Q, Zhang Z, Dong F, Chen L, Zheng L, Guo X, et al. Anterior insula GABA levels correlate with emotional aspects of empathy: a proton magnetic resonance spectroscopy study. PLoS One. 2014;9:e113845. https://pubmed.ncbi.nlm.nih.gov/25419976/
56. Luscher B, Shen Q, Sahir N. The GABAergic deficit hypothesis of major depressive disorder. Mol Psychiatry. 2011;16:383–406. https://pubmed.ncbi.nlm.nih.gov/21079608/
57. Filip M, Frankowska M. GABA(B) receptors in drug addiction. Pharmacol Rep. 2008;60:755–70. https://pubmed.ncbi.nlm.nih.gov/19211967/
58. Morris MC, Tangney CC, Wang Y, Sacks FM, Barnes LL, Bennett DA, et al. MIND diet slows cognitive decline with aging. Alzheimers Dement. 2015;11:1015–22. https://pubmed.ncbi.nlm.nih.gov/26086182/
59. Morris MC, Tangney CC, Wang Y, Sacks FM, Bennett DA, Aggarwal NT. MIND diet associated with reduced incidence of Alzheimer’s disease. Alzheimers Dement. 2015;11:1007–14. https:/