Sleep Structure
Sleep is a complex physiological and behavioral process. According to the changes in brain electrical performance, eye movements and muscle tension during sleep, it is generally categorized into NREM (non-rapid eye movement) sleep and REM (rapid eye movement) sleep, of which NREM sleep covers light sleep and deep sleep.
Normally, wakefulness, light sleep, deep sleep and REM phase alternate once in sequence to form a sleep cycle lasting 90 - 120 minutes. During the night, there are about 4 - 6 sleep cycles occurring consecutively, and the cycle is repeated.
It should be noted that the above sleep stages are divided for research purposes. In reality, it is difficult to establish clear boundaries between the stages of sleep, and they are often gradual, interlaced, and have their own focus.
Light Sleep
When adults go from wakefulness to sleep, they first enter the light sleep stage. At this time, EEG activity gradually slows down, heartbeat and breathing tend to slow down, muscles relax further, body temperature drops slightly, and eye movement stops. During this stage, people are more sensitive to external stimuli and are easily awakened. Waking up from sleep is the body's protective mechanism and a normal physiological need. However, if the proportion of light sleep in the total sleep time is too high, the quality of sleep will be affected, and you may feel that you have not slept enough and are not tired when you wake up.
Reference range: <55%
Deep Sleep
During the deep sleep stage, the brain wave frequency slows down significantly, and the breathing rate and blood pressure drop significantly. It is also called slow-wave sleep. At this time, the sleep level is the deepest and it is difficult to wake up. If you are awakened, you may feel a little uncomfortable. During this stage, the brain can fully rest and eliminate fatigue. It is very important for stabilizing emotions, balancing mentality, and restoring energy. Usually, the longer the deep sleep time, the better the sleep quality.
Reference range: 20%-60%
REM Sleep
During the REM sleep period, muscle tension disappears, and various physiological indicators are active and unstable. Muscles that can be controlled freely at ordinary times temporarily lose strength, heart rate and breathing speed up, and body temperature regulation functions are mostly lost. It is not easy to be awakened at this stage, and people who wake up from here can often clearly recall their dreams.
Reference range: 10%-30%
Awake
During sleep, due to external factors (such as noise, light) or personal factors (such as getting up at night, physical discomfort), the awake state will appear. Sometimes awakening is fleeting and difficult to detect. Under normal circumstances, adults wake up less frequently at night, generally no more than twice, and the proportion of awake time at night is usually less than 5% of the whole night's sleep, and the cumulative duration is generally less than 20 minutes.
Reference range: 0-1 times
Common questions
Q1: There is sleep but no sleep record is generated
1) The movement amplitude is too large during sleep (such as frequent and large turning over), and the sensor of the watch is difficult to accurately capture the sleep state signal, resulting in no sleep record.
2) On moving and bumpy transportation such as buses and trains, the watch is disturbed by continuous shaking, and the sleep state cannot be accurately judged, and no record is generated.
3) The watch is worn too loosely and does not fit tightly to the skin during sleep, which may be misjudged as being off the wrist and stop sleep monitoring.
4) The sleep duration is too short (less than 20 minutes). Due to the limitation of the monitoring mechanism, the watch cannot recognize this sleep and generate a record.
Q2: Sleep records are generated without sleep
1) If you are still for a long time (such as lying down to read a book or sitting for a long time), the movement amplitude and frequency are similar to the sleep scene, and the watch misjudges it as sleep based on the algorithm.
2) When the watch sensor is placed on a table, sofa or other objects with the light change facing down, the received signals such as light changes are similar to the state of being worn on the wrist. Because it cannot sense living bodies, sleep monitoring is mistakenly started and records are generated.
Q3: Inaccurate sleep time and number of awake times
1) If you turn over unconsciously and continuously during sleep, the watch may recognize this action as awake; if the movement amplitude is small after waking up, it is difficult for the watch to detect that you have woken up, resulting in misjudgment of the number of awake times and time.
2) If you are in a relatively static state before going to bed (such as lying down to read a book), the watch mistakenly determines this state as sleep, making the recorded sleep time advanced.
3) If you lie in bed and do not move after waking up, the watch misjudges that you are still asleep based on the original monitoring logic, resulting in a delay in the time of waking up.
Q4: Inaccurate sleep records
1) After the watch is separated from the human body, if the chip side is placed on the table, the heart rate chip may misjudge that the user is in a static state, interfering with the accuracy of sleep records.
2) When the watch is in a static state, the heart rate chip may misjudge that the indicator is similar to the sleeping state when the watch is in a static state because sleep monitoring needs to be combined with heart rate, activity status and other factors, resulting in recording deviation.
3) Sleep data is affected by many factors such as sleep habits, movement amplitude, and watch fit. It is for reference only and cannot be used as a medical or authoritative report.