To make white sugar, sulfur dioxide is added to cane juice before it gets evaporated. This gas does the bleaching of the juice so that it does not turn brown and produces white sugar. At later stages, phosphoric acid, calcium hydroxide or carbon dioxide is added to absorb impurities.
The first REM sleep period usually occurs about 70 to 90 minutes after we fall asleep. A complete sleep cycle takes 90 to 110 minutes on average. The first sleep cycles each night contain relatively short REM periods and long periods of deep sleep.
As the night progresses, individuals spend increasingly more time in REM sleep and correspondingly less time in deep sleep. How long is a sleep cycle? The first sleep cycle takes about 90 minutes. After that, they average between 100 to 120 minutes. Typically, an individual will go through four to five sleep cycles a night. What Is Deep Sleep? Stages 3 and 4 are referred to as deep sleep, slow wave sleep, or delta sleep.