Sleep is the most powerful recovery tool available to any athlete. Here is what actually determines whether yours is good or not.
Getting enough sleep is important to your overall health. Everyone's optimal amount varies, but global studies have shown most people need between seven and nine hours per night. On average, adults need about 8 hours and 10 minutes.
Sleep duration is essential for a good night's recovery, but it is only part of the picture. While asleep, the brain goes through four to six cycles per night, each lasting around 90 minutes. These cycles consist of three key stages alongside brief periods of wakefulness.
REM sleep is the dreaming stage, essential for cognition and emotional health. It lasts 10 to 60 minutes per cycle and makes up 15 to 25% of total sleep.
Core sleep (N1 and N2) is the initial light sleep stage where eye and muscle movements slow down. It lasts 10 to 25 minutes per cycle and makes up 55 to 75% of total sleep.
Deep sleep (N3) involves no eye or muscle movement and is critical for immune function and recovery. It lasts 20 to 30 minutes per cycle and makes up 10 to 20% of total sleep.
Awake periods are brief, usually 1 to 5 minutes, and account for less than 5% of total sleep time.
Unspecified is how Apple Watch labels naps and snooze periods, indicating only that you were likely asleep without specifying the sleep phase.
Restorative sleep is the combination of deep and REM sleep. It is when your brain and body undergo vital repair and healing.
Deep sleep is the physically restorative stage, where the body releases growth hormone, repairs muscles, promotes tissue growth, and supports immune health.
REM sleep is the mentally restorative phase. It is when dreaming occurs and short-term memories turn into long-term ones. It also enhances learning, cognitive function, and cellular regeneration.