A headlamp or a small flashlight is one of the essentials that you should have with you even on a day hike.
You might end up getting back later than you planned. I’ve gotten lost in the mountains on a day hike and have had to hike back to my car in almost total darkness. It might get dark sooner than you think because of heavy cloud cover or if you are in a dense forest.
A headlamp has many advantages over a small flashlight.
First of course is that it leaves your hands free. This is handy when you are walking because otherwise it would be difficult to use your hiking poles. But it’s essentially comfortable when you are doing something with your hands, like setting up your tent or your tarp, cooking, setting up a fire or looking for something in your backpack.
Better as a reading light
Weather you’re reading a book before falling asleep or studying a map, a headlamp is much more comfortable to use.
Harder to lose
You can always turn off your headlamp when you want to look at the stars or the campfire and turn it back on when you need the extra light. It’s on your person so you won’t have to look for it and there’s much less chance you’ll misplace it somewhere where you can’t find it in the darkness.
Bring extra batteries
Don’t forget to bring extra batteries for your headlight. You should have at least one set of fresh batteries in case they run out. In the winter, keep the spare batteries in the inside pocket of your jacket to prevent them from getting drained by the cold.
Don’t blind other hikers
Many headlamps offer options for brightness. Be considerate to other hikers when you meet them on the trail or in the campsite and avoid blinding them with your headlamp.
I also suggest you read my post about everything you need to go day-hiking and also check out my ultimate hiking gear check-list which you can also download as a PDF to make sure you never forget any of your essential gear and clothes when you leave home for a hiking trip.