Related by context. Frequent words. (Click for all words.) 65 wakefulness 56 arousal 56 circadian 55 sleep 52 daytime sleepiness 52 brainstem 52 awakenings 52 circadian rhythm 51 cortex 51 visual cortex 51 cognition 50 ghrelin 49 sleepiness 49 cognitive 49 hippocampus 49 cortical 49 circadian rhythms 49 neurons 49 cognitive function 48 melatonin 48 cortisol 48 neurogenesis 48 apnea 47 brain circuitry 47 snore 47 cerebral cortex 47 sleep disturbances 47 cognitive functioning 47 striatum 46 Sleep apnea 46 cortisol levels 46 synapses 46 serotonin 45 norepinephrine 45 basal ganglia 45 cerebellum 45 neural 45 cognitive functions 45 synaptic 45 cognitive impairment 45 neurones 45 brainwaves 44 amygdala 44 insulin secretion 44 ADHD symptoms 44 hallucinations 44 glucose metabolism 44 syncope 44 neuron 44 depressive symptoms 44 brain 44 leptin 44 dopamine 44 satiety 44 secretion 44 psychotic symptoms 44 metabolism 44 metabolic 44 prefrontal cortex 43 BDNF 43 obstructive sleep apnea 43 auditory 43 menstrual cycle 43 motor cortex 43 orgasm 43 Melatonin 43 sleep deprived 43 ejaculation 43 oxygen saturation 43 mutant mice 43 ventricular fibrillation 43 cognitive decline 43 skeletal muscle 43 SIRT1 43 mild cognitive impairment 43 stress hormones 43 cognitive abilities 43 temporal lobe 42 sleep disordered breathing 42 stress hormone cortisol 42 cognitive deficits 42 adenosine 42 adrenal 42 perceptual 42 somnolence 42 schizophrenics 42 lung function 42 snoring 42 waking 42 physiologic 42 drowsiness 42 thalamus 42 neuronal 42 circadian clock 42 tinnitus 42 RLS 42 awake 42 erections 42 brain stimulation 42 frontal lobe 42 acetylcholine