Improved measurement of sleep stages.
D000293:Adolescent; D000368:Aged; D003700:Delta Rhythm; D003866:Depressive Disorder / Q000503:physiopathology; D004569:Electroencephalography; D006801:Humans; D012107:Research Design / Q000592:standards; D012894:Sleep Stages / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology