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.
Sleep problems are common in the elderly. In general, the amount of sleep needed stays constant throughout the adult years. Doctors recommend that adults get 7 to 8 hours of sleep each night. In older adults, sleep is less deep and choppier than sleep in younger people. A healthy 70-year-old may wake up several times during the night without it being due to disease. Some causes or contributors to sleep disturbances in older adults include: 1  Alzheimer disease. 2  Alcohol.  Changes in the body's natural internal clock, causing some people to fall asleep earlier in the evening)