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.
Confidence votes 118. The sensation of falling as you fall asleep is known as hypnagogic myoclonic twitch or Hypnic jerk. Most experts agree that this is a natural part of the sleeping process, much like slower breathing and a reduced heartbeat. The occurance is well known and has been well documented.