A high-tech technique to create silence is to use a set of in ear noise cancelling headphones. These use the principle of anti-noise to create silence. What this means is that the headphones create a noise that is 180 degrees out of phase with the noises in the outside environment. This has the effect of cancelling out the original noise. Noise-cancelling headphones work best on low frequency noises, regular noises, like the sound of airplane engines. They don't work as well on things like conversations, unless you are playing music at the same time.
Depending on how enthusiastic the cabin staff are, this may be easier said than done. And if that child behind you rocks your seat once more, then that's another story. If you get the option, a window seat or one in the center of a block of seats will minimize the number of people who need to ask you to move out of their way. Noise reducing headset aren't standard issue on many flights, so if you are a regular traveler then treat yourself to a set. They really do cut down the disturbance of engine noise.
These had better be free to start. Well, you might need a bit of your own equipment, such as a good Noise Cancelling Headset if you want to do customer service, but the employer shouldn't be charging you.
Now that you know what to pack your stuff into, let's go into what you can pack. Most travel gadgets happen to be electronic, or happen to be very clever. Here's one that's neither, but is still extremely useful. It's an all-in-one tool, a Swiss Army knife. When you're out there on the Himalayan foothills, and you ride sputters out, you'll probably kill for one of these. Look at the Leatherman series for some great action when you need it. Some of the models come with pliers to help you strip electrical insulation off, a screwdriver to help you fix the handle of a broken suitcase, a pointy point to help you press a Reset button, and so on. The best part is, they'll cost you no more than $50 at Amazon, if you go for the top-end stuff.
Enjoy your trip and try not to let the frustration of lost sleep ruin your time. Even if you can't fall into deep sleep, every bit of rest does count.