Related by context. Frequent words. (Click for all words.) 77 drowsiness 63 sleeplessness 62 tiredness 61 irritability 60 insomnia 58 wakefulness 58 sleep disturbances 58 drowsy 56 sleep disorders 55 fatigue 54 alertness 52 sleep deprived 52 hypoglycemia 52 caffeine intake 52 depressive symptoms 52 sleep 51 dizziness 50 arousal 50 sleep deprivation 50 binge eating 50 hot flushes 50 impulsivity 49 hyperactivity 49 circadian 49 hallucinations 49 melatonin 49 psychotic symptoms 49 REM sleep 49 symptoms 49 apnea 49 ADHD 49 disorientation 49 sleep apnea 49 snoring 49 muscle cramps 48 nausea 48 circadian rhythm 48 nausea vomiting 48 overeating 48 mood disorders 47 caffeine 47 psychological distress 47 forgetfulness 47 depression 47 narcolepsy 47 cognitive impairment 47 obstructive sleep apnea 47 breathlessness 47 restless legs 47 jet lag 47 generalized anxiety disorder 47 migraines 46 boredom 46 palpitations 46 impulsiveness 46 falling asleep 46 vomiting 46 circadian rhythms 46 dyspnea 46 tinnitus 46 constipation 45 Sleep apnea 45 stuffy nose 45 body aches 45 cortisol levels 45 depression anxiety 45 restlessness 45 migraine 45 doze 45 fluid retention 45 vomiting diarrhea 45 fluoxetine 44 satiety 44 migraine sufferers 44 cognition 44 cognitive deficits 44 nasal congestion 44 allergy symptoms 44 inebriation 44 cognitive function 44 cortisol 44 risky behaviors 44 abdominal pain 44 inattention 43 hot flashes 43 chronic cough 43 cravings 43 cognitive functioning 43 suicidality 43 hyperglycemia 43 Attention Deficit Hyperactivity Disorder 43 lethargy 43 antihistamines 43 hypotension 43 serotonin 43 moodiness 43 slurred speech 43 suicidal thoughts 43 insomniacs 43 numbness 43 hypoxia