Related by context. Frequent words. (Click for all words.) 48 melatonin 45 Melatonin 44 acetylcholine 44 stress hormones 44 cortisol 44 chemical dopamine 44 histamine 43 adenosine 43 chemical messengers 43 Cortisol 43 stress hormone cortisol 42 nitric oxide 42 orexin 41 prolactin 40 secretion 40 dopamine neurons 40 Oxytocin 40 serotonin 40 vasopressin 40 dopamine 40 ghrelin 40 nicotine 39 glutamate 39 norepinephrine 39 pheromone 39 oxytocin 39 neurotransmitter dopamine 39 pheromones 38 glucocorticoid 38 sebum 38 platelet aggregation 38 inflammatory cytokines 38 harmful toxins 38 neurotransmitter 38 retinoic acid 38 endorphins 38 theobromine 37 ovulation 37 PYY 37 arousal 37 insulin secretion 37 wakefulness 37 prostaglandins 37 stomach acid 37 sexual arousal 37 cAMP 37 Dopamine 37 pharmacologically 37 NPY 37 cytokines 37 Nicotine 36 C reactive protein 36 cortisol levels 36 mitochondrial function 36 neurochemical 36 androgens 36 REM sleep 36 gabapentin 36 melanin 36 neuronal activity 36 interleukin 36 neurotransmitters 35 receptors 35 digestive enzymes 35 prostaglandin 35 valproic acid 35 alkaloids 35 leptin 35 sleep 35 ketones 35 EGCG 35 electrical pulses 35 riboflavin 35 male hormone testosterone 35 endorphin 34 muscle contractions 34 mucus 34 signaling molecules 34 angiotensin II 34 hormone insulin 34 zolpidem 34 insulin 34 immune cells 34 cytokine 34 estradiol 34 skeletal muscles 34 Leptin 34 hormone 34 biochemical reactions 34 anti oxidant 34 neural pathways 34 glutathione 33 excitability 33 adiponectin 33 circadian rhythms 33 nerve cells 33 satiety 33 anthocyanins 33 arginine 33 external stimuli 33 polyphenol