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.
On average, about one-third of a person's life is spent sleeping. However, the amount and timing of sleep vary considerably in different people, based on their age and lifestyle. Newborn infants may sleep up to 20 hours a day. Young and middle-aged adults sleep about 8 hours on average. Elderly people tend to get less sleep at night but may take naps during the day.