Open your favorite media player in my case Videolan start you favorite web radio station like Metal Nation Web Radio and a terminal.Type

 sudo shutdown 07:30

 we need administration privileges so sudo time is let say 06:52 we need the system to shutdown in 38 minutes so we say to the system to shutdown 7:30 and our timer is setup.

 
Options:
  -r                          reboot after shutdown
  -h                          halt or power off after shutdown
  -H                          halt after shutdown (implies -h)
  -P                          power off after shutdown (implies -h)
  -c                          cancel a running shutdown
  -k                          only send warnings, don't shutdown
  -q, --quiet                 reduce output to errors only
  -v, --verbose               increase output to include informational messages
      --help                  display this help and exit
      --version               output version information and exit

You can also add a message

sudo shutdown 7:30 "Goodnite penguins"

Happy linux radio time (if you can sleep count penguins helps.)