This is the US version of the bugle call Reveilleed by military forces to wake up the soldiers at the start of the day. In other countries alternative calls are used for the same purpose including Rouse, The First Post and two non-US versions of Reveille known as Long Reveille and Charlie Reveille. Other calls are used to mark the end of the day such as The Last Post and Taps. See the links at the left to download the sheet music or audio files. More bugle calls are listed in our article about the history and cultural impact of Bugle Calls
The image below is the first page of the sheet music, and here you can download the full sheet music for Reveille (US bugle call) in PDF format.