这是因为在非快速眼动睡眠中，自动的新陈代谢系统对呼吸有排他的控制，身体消耗更少的氧气，产生更少的二氧化碳。

This occurs because during NREM sleep the automatic, metabolic system has exclusive control over breathing and the body uses less oxygen and produces less carbon dioxide.

youdao

第二，一旦完全进入睡眠状态，非快速眼动期间血液中的二氧化碳增加，氧气减少。

Second, once sleep is fully obtained, there is an increase of carbon dioxide and a decrease of oxygen in the blood that persists during NREM.

youdao

睡眠过程中，你在两种睡眠状态中转换，快速眼动期(REM)和非快速眼动期(non - REM)，90分钟一个循环。

During sleep, you drift between two sleep states, REM (rapid eye movement) and non-REM, in 90-minute cycles.

youdao