Sleep is a natural state of REST that is essential for physical and mental health. Apnea is a sleep disorder characterized by pauses in breathing during sleep. INERTIA is the tendency of an object to remain at REST or in motion unless acted upon by an outside force. REM stands for Rapid Eye Movement, which is a stage of sleep characterized by dreaming. A NAP is a short period of sleep, usually during the day. DOSS is an informal term for sleep or doze. Onit is an informal term for sleep or doze. REST is a state of inactivity or REPOSE. SOPOR is a deep sleep or lethargy. REPOSE is a state of REST or tranquility. SNOOZE is an informal term for a short period of sleep. Shuteye is an informal term for sleep. SLUMBER is a deep sleep. Getsomesacktime is an informal term for getting some sleep. Inheavenlypeace is an informal term for sleeping peacefully.