AHK time-sensitive loops

FormatTime startTime, 20051231020000, HH ; 2005 Dec 31 02:00:00; the actual date does not matter
FormatTime endTime,   20051231160000, HH ; 2005 Dec 31 16:00:00; the actual date does not matter
Loop {
    FormatTime currTime, , HH ; If the second value is blank then it takes the current time
    if (startTime < currTime and currTime < endTime) {
        ; Do your stuff
    }
    Sleep % 30 * 60 * 1000 ; stop execution for 30 mins (can be reduced as needed)
}

; Alternatively, if the "your stuff" needs to repeat:

FormatTime startTime, 20051231020000, HH
FormatTime endTime,   20051231160000, HH
Loop {
    FormatTime currTime, , HH
    if (startTime < currTime) {
        Loop {
            ; Do your stuff
            if (currTime > endTime) break
            Sleep 20 * 1000 ; 20 seconds (can be reduced as needed)
        }
    }
    Sleep % 30 * 60 * 1000 ; stop execution for 30 mins (can be reduced as needed)
}