Turn on/off monitor

[DllImport("user32.dll")]
static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);

private const int WM_SYSCOMMAND = 0x0112;
private const int SC_MONITORPOWER = 0xF170;
private const int MonitorTurnOn = -1;
private const int MonitorShutoff = 2;

//Turn them off
SendMessage(f.Handle, WM_SYSCOMMAND, (IntPtr)SC_MONITORPOWER, (IntPtr)MonitorShutoff);

//Turn them on
SendMessage(f.Handle, WM_SYSCOMMAND, (IntPtr)SC_MONITORPOWER, (IntPtr)MonitorTurnOn);