Elizabeth: I’ve taken them on a couple of red eyes and I think they help!
According to the instructions, you should take one tablet at take-off, then one every two hours, then one more when you arrive to help with relaxation and combat sleepiness. (Though if you fall asleep during the flight, it’s OK to go up to four hours between tablets.)
Promising review: “I heard about this product from my cousin, who used it for a trip to Japan, and it was very effective. I used it for a trip to Washington, DC that had several stops and delays — a total of 15 hours to get to my destination. I was comfortable upon arrival. The next morning I was ready for a workday.” —Eleanore
Get a pack of 32 pills from Amazon for $15.99.