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.
Those who slept for fewer than seven hours a night had more sickness. The lead author, Kathryn Orzech, says research shows that teenagers need 9.5 hours sleep a night, but on average get only 7.5 hours. But this doesn't mean that it is normal for teenagers not to get enough sleep, says Orzech.