First of all, the millet wristband 2 has built-in accelerometer and photoelectric rhythm sensor. The data monitored by these two sensors is the basis for judging whether my Xiaomi Mi Band track my in deep sleep or not. The acceleration sensor can monitor whether the position of the hand ring is moving great technology. In deep sleep state, the human arm is basically not moving. Studies have shown that the light sleep period and light sleep period, which account for about 55% of the total sleep time, have little effect on fatigue relief.
And only enter the deep sleep state in the middle of sleep, deep sleep and rapid eye movement sleep, only to relieve fatigue have a greater effect. Because in the deep sleep state, the cerebral cortex cells are in a state of full rest, but there is a large error in the acceleration sensor of the light. For example, when the user forgets to wear the wristband, the wristband may depend on the acceleration sensor to determine that the user is all night long. Deep sleeping. you can buy it from amazon
Photoelectric heart rate sensors can monitor heart rate, Photoplethysmography (PPG), to monitor heart rate. The principle is simple: the blood is red, reflects red light, and absorbs green light. Millet Bracelet 2 combines green LED light with a photosensitive photodiode to measure the amount of blood circulating at the wrist at a given time to obtain heart rate information.
Bracelet 2 also monitors the heart rate of the user from time to time during daytime wear. Heart rate fluctuations during daily work are greater than during sleep. When the body enters deep sleep, the cerebral cortical cells are in full rest, and the heart rate is also much smoother than during the day. .
The two sensors’ data is the basis for judging whether people are in deep sleep.
What is interesting is that Apple’s mobile phone once had a very interesting function to monitor sleep time. When using it, it needs to keep the mobile phone charged. The mobile phone is placed within 50cm from the user’s bedside, and the mobile phone’s charging port faces the user. The next day will be able to Seeing that the sleep time is recorded, and the data is more accurate, the principle of this function is that the phone’s microphone collects the user’s late night at night, and judges whether the user is asleep through the size of the sound.
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