As a respiratory expert with a focus on sleep medicine, I can provide you with information regarding normal blood oxygen levels during sleep. Normal blood oxygen levels, also known as oxygen saturation, are typically around 95-100% when you are awake and breathing room air. However, it's important to note that oxygen levels naturally decrease slightly during sleep due to the body's relaxed state and the reduced effort of breathing. This is a normal physiological response and is not typically a cause for concern unless the drop is significant. The reference you provided suggests that if your oxygen saturation is greater than about 94% while awake, it is unlikely that it will fall below 88% during sleep. This is generally considered the lower threshold for normal oxygen saturation levels during sleep. However, it's important to remember that individual factors can influence these levels, and what is considered normal can vary from person to person. It's also worth mentioning that certain conditions, such as sleep apnea, can cause significant drops in blood oxygen levels during sleep. If there are concerns about sleep quality or breathing during sleep, it's important to consult with a healthcare professional for a proper evaluation. read more >>

Everyone's oxygen levels in the blood are lower during sleep, due to a mildly reduced level of breathing. Also, some alveoli drop out of use during sleep. If your waking oxygen saturation is greater than about 94 percent on room air, it is unlikely that your saturation during sleep will fall below 88 percent.read more >>