Related by context. Frequent words. (Click for all words.) 76 melatonin 70 pineal gland 67 Melatonin 65 serotonin 65 Cortisol 64 neurotransmitter dopamine 64 orexin 63 chemical serotonin 63 chemical dopamine 61 circadian rhythms 61 hormone 61 circadian 60 circadian rhythm 59 female hormone estrogen 59 cortisol 59 neuronal activity 59 brain derived neurotrophic 59 circadian clock 58 stress hormones 58 acetylcholine 58 thyroid hormones 58 thyroid hormone 58 prolactin 58 biochemical pathway 58 aromatase 57 hormone estrogen 57 chemical messengers 57 nitric oxide 57 dopamine 57 Leptin 57 prostaglandins 56 steroid hormones 56 adenosine 56 stress hormone cortisol 56 aldosterone 56 leptin 56 inflammatory cytokines 56 glutamate 56 hormones 56 metabolic processes 56 Nitric oxide 56 hormone insulin 55 nitric oxide NO 55 neurogenesis 55 vasopressin 55 NPY 55 insulin secretion 55 synaptic plasticity 55 SIRT1 55 secretion 55 arachidonic acid 55 neurotransmitter 54 biochemical processes 54 Serotonin 54 neurochemical 54 metabolism 54 signaling molecule 54 ghrelin 54 glucocorticoid 54 platelet aggregation 54 neurotransmitters 54 retinoic acid 54 NMDA receptors 54 dopamine neurons 54 wakefulness 54 superoxide 54 GABA 54 adiponectin 54 pro inflammatory cytokines 54 cAMP 53 interferon gamma 53 androgens 53 mitochondrial function 53 glucose metabolism 53 molecular mechanism 53 auxin 53 ceramide 53 Dopamine 53 hypothalamus 53 neuroendocrine 53 cytokine 53 molecular pathway 52 estrogen 52 alkaloid 52 dopamine receptors 52 brain circuitry 52 NF kB 52 angiotensin II 52 autonomic nervous system 52 norepinephrine 52 NMDA receptor 52 REM sleep 52 naturally occurring protein 52 enzyme 52 PPAR gamma 51 cytokines 51 BDNF 51 hepcidin 51 cortisol levels 51 tyrosine 51 vascular endothelial growth