Sandstone: Rock for Crack Climbing. Sandstone is a sedimentary rock, a rock type that encompasses a wide variety of characteristics and is deposited directly on the earthâs surface. Roughly 75% of the earthâs land surface is covered with some type of sedimentary rock. Sedimentary rocks like sandstone form when minute rock particles, often from granite, are deposited by wind and water on earth surfaces.
8. 1  Other Causes. 2  Diabetes causes arms or hands and feet to fall asleep even when one is awake and relaxed. 3  Hand surgery and arthritis damage or irritate the nerves.
Narcolepsy is related to the deep, dreaming part of sleep known as rapid eye movement (REM) sleep. Normally when people fall asleep, they experience 90 minutes of non-REM sleep, which is then followed by REM sleep. People with narcolepsy, however, enter REM sleep immediately.