What are these disruptive passengers or snorers you guys are coming across doing that make them louder (and able to cut through plane noise) more than a crying child?! Would love to hear those stories as I can't picture it.

Anyway, having flown too many JFK > LHR red-eyes to count in the front 2 cabins I've been fortunate in the small child department. If it ever is an issue however, there are 5 steps to make it a non-issue, 3 of which don't involve any ill-effects on the body.

Step 1: Earplugs
Step 2: Overhead noise cancelling headphones (over the ear plugs)
Step 3: Play white noise / classical / audiobooks / podcasts
Optional step 4: Alcohol
Optional step 5: Melatonin (or insert other chemical aid)

If you are taking red-eyes for more than just a one-off; be prepared to do the above.