health

Biology & Medicine

Sleep

• Sleep ApneaIn obstructive sleep apnea (OSA), the upper airway repeatedly narrows or collapses during sleep even though the chest is still trying to breathe. Each event can reduce airflow/oxygen and trigger a brief arousal, producing fragmented sleep that the sleeper may not remember.
• Sleep ArchitectureA normal night's sleep is not eight hours of one state. The brain repeatedly cycles through N1 N2 N3 back toward lighter NREM REM, with the mixture changing over the night.