nap mind wear baby tear Lack cold rise turn anger adult study joints result people repair feeling stomach subject seconds viruses muscles acidity Research bacteria next day Body ache Arthritis heartburn esophagus REM sleep bad sleep agitation condition entire day good sleep poor night one factor resistance Good Night activities acid reflux Throat ache Mood swings Rheumatology vulnerability major factors understanding other factors tissue growth complete sleep sleep disorders unrestful sleep disturbed sleep Widespread pain healing process growth hormones satisfying thing first indicators sleep deprivation daytime sleepiness improper functioning consecutive episodes proper sleep pattern bad morning headaches esophageal sphincter valve