Okay, I'm not much up to date on all the latest digital stuff. I will admit that. I used to take my iPod so I could listen to music and fall asleep out in the wilderness. Now suddenly I found out they are no longer making (and supporting?) the iPod. What is the replacement? I could take my iPhone, but the batteries would not last long listening to music, or so I am told. Plus the batteries don't even last long when it is tracking my hike on a GPS app.
A boom box would be to heavy!

I still have a couple of SanDisk Sansa Clip+ mp3 players, which are simple, lightweight, durable, and the batteries last a long time. That model is discontinued, but the newer version (SanDisk Clip Sport Plus) looks similar and gets excellent reviews:
https://www.amazon.com/SanDisk-SDMX28-016G-G46K-Sport-Player-Black/dp/B01LW2F237

You don’t say what model iPhone you have and there are various power banks that will charge iPhones that hikers and backpackers take along for that purpose. Some of the newer models accept magnetic units that attach to the back of the phone. I use AirPods so there is not much power draw off the phone. One does have to charge those too. I’ve never worn them while trying to fall asleep though.

The nice thing about iPhones is audiobooks, ebooks, music, gps navigation, night sky apps, podcasts and so forth. I’d say the camera apps get used the most. Since you have an iPhone just try it at home and see how long the battery lasts and choose the power bank that will get you through.

Are you putting the phone in airplane mode when you're hiking? That would help save battery life.

thanks Arizona. I will look into battery packs for the phone. Incidentally, I have since found MP3 players that are relatively cheap (<$30) that are very light weight and claim like 70 hours of battery life. Half that would work for me.

Thanks for reminding me about airplane mode. However I suspect that my gps tracking (Giga for example) would not work so I would not have the distance, elevation gain for the hike.

Tom, yes, I did discover there were such devices available. Scandisk was rated one of the best. The reviews of AGPtek say it is simple but looks like it would work for me and is less expensive. Thanks for your comments. Jim

GPS works in airplane mode in (most? all?) iphones since they have a separate gps chip. Turning on airplane mode will stop the cellular chip from constantly trying to connect, which kills the battery pretty quickly when you're not in cell range. You can turn bluetooth back on if you need it, but leave cellular off, and you'll see much better battery life while still having gps capabilities.

Good advice and I concur that gps works while in airplane mode. That’s how I carry while in wilderness always in airplane mode. That also turns off WiFi that will also keep trying to connect and waste battery as well as cellular.

If you’ve ever been tent bound for several days the entertainment will be so appreciated. That’s why I keep music, audiobooks, podcasts and ebooks downloaded before hand. But the little mp3 players are indeed light with long battery lives. However another way to increase battery life for the iPhone is to turn off the screen display while listening.