Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. Just a few weeks ago, I had a long-haul flight to Europe from the East Coast. As I packed and prepared, excited about what was planned, I also wondered and worried: How the heck was I going to sleep on this eight-hour flight, so I wasn’t sleepwalking through sightseeing the next day? It’s a conundrum many of us have faced. There are TikTok videos, articles, products, and advice galore about how to meet the challenge. But what exactly does the science say? What’s the best way to sleep on a plane?   Popular Science went to the experts. Here’s why it’s so difficult to get sleep on a plane, and how to set yourself up for the best chance of getting some shut eye up in the air. Why it’s so hard to sleep on planes  Nearly every environmental cue is working against us on planes , making it near impossible to get to sleep.…