Good Night Flights

Just need to be sure on this, am I right in thinking that the Good Night flights only operate on overnight flights from east coast USA to London? I'm keen to avoid ending up in the snooze zone on our flight to DXB in April! Given that the flight departure time & duration for LHR-DXB is similar to that of BOS-LHR (which operates as a Good Night flight), and they're both eastbound overnight flights I thought I should check?
Thanks,
James
Thanks,
James