...but I figured I'd go ahead and post the "duty hours" here, as well. 
Standard shifts are eight hours long, and flow as follows:
Alpha: 0700-1500
Beta: 1500-2300
Gamma: 2300-0700
A responsible officer should expect to be at their duty station a good fifteen minutes before the shift starts, so as to get report and be up to speed.
Medical shifts are twelve hours long, and instead take the following schedule:
Alpha: 0700-1900
Beta: 1900-0700
Typically medical shifts are referred to as "Sickbay Alpha, Sickbay Beta" so as to avoid confusion.