Run in the Dark? One Runner Puts 2 Petzl Headlamps to the Test

Need to light your way on an early-morning run or logging miles after dark?

Runner Lucie Hanes put two Petzl headlamps to the test.

Here's what she learned...

Run in the dark? 6 challenges for runners

The days are getting shorter, but the to-do lists stay just as long…which means that many runners end up heading out for their miles outside of the sun’s regular schedule. 


If you run in the early-morning hours before sunrise or lace up for night runs, there's at least six challenges with running in the dark to consider:

  1. Mental toughness. Running through the dark is hard enough from a mental standpoint.
  2. Body-clock fatigue. Your circadian rhythms are begging you to wind down
  3. More clothing required: Dressing for the weather becomes no less than a twenty minute affair
  4. Your bed vs. nature: The cold air awaiting you makes a warm bed feel that much more appealing. It feels like a battle against nature to even get out the door. 
  5.  Visibility. But the struggle doesn’t end once you’re up and at ‘em. There are plenty of extra precautions runners should take in the dark. You need a reliable way to see, and be seen, when the sun’s not there to guide your way. 

Even if you run in a well-trafficked area, you can’t count on streetlights to illuminate your whole route. 

And if you’re on trail or anywhere outside of the city limits, you’re completely on your own. 

Choose, but choose wisely. Not all headlamps are the same.

The right headlamp can mean the difference between:

  • A successful pre-dawn run and a scary wildlife encounter
  • Run-ins with unsavory characters, or
  • A broken ankle from tripping on a root hidden in the shadows. 

With a good headlamp, you’ll be able to see what’s ahead and prepare for it instead of getting caught off-guard when your mind’s still shaking off the sleep. 

But the best headlamp is the one you actually use.

  • To be worth bringing along on a run, it needs to help more than hinder. 
  • That means going unnoticed except for a steady stream of light, as if the beam came out right out of your forehead itself. 

The headlamp lesson that almost left me in the dark

On my first overnight race, a 24 hour relay in Moab, my headlamp bounced and fell out of place.

Not once or twice. But over and over as the night wore on.

I ended up taking it off completely and trying to keep pace with the one other runner on the same lap schedule as me. 

That's not an ideal way to run in the dark. I kept thinking:

What if there was no one else around at 2AM in the desert?

From that moment on, I knew I needed a headlamp that's more subtle and more reliable so that I could feel safe out there on my own.

Give these TWO Petzl headlamps a try

Petzl is best known as a manufacturer of technical equipment for climbers and at-height laborers. 

But they’re also the leader in lighting technology for outdoor athletes. 

Two of their most popular and affordable headlamps cover all these bases in different ways. 

Depending on where, why, and how you run, you’ll find your match in either:

And the best part? You’ll barely know it’s there either way.

I put these two Petzl headlamps to the test. Here's what I learned:

On the outside, the Swift RL looks like your basic camping headlamp:

  • Stretchy band
  • Boxy lamp
  • Adjustable fit

There’s a reason most headlamps look like this: It’s a simple design that ticks the boxes. 

But the Swift hides a good number of bells and whistles inside its basic exterior. 

The headband

For one, the headband actually stays in place. 

  • Split design: It’s split in two along the back for better weight distribution than most headlamps, and the grippy fabric keeps it from sliding around with every stride. 
  • Adjustable. A quick tug to either side makes it easy to adjust on the go without even having to take it off. 
  • Extra padding up front keeps the lamp from digging into your forehead, too—which means no more red outlines that earn you some weird looks in your first post-run meeting of the day.
  • Stability. The stability of the strap keeps the lamp itself from bouncing. Even though the lamp casing does extend outward a good inch from your forehead, it doesn’t slip. (Fun fact: I’ve jumped, leaped, and even cartwheeled to try and knock it out of place to no avail.)
  • Weight: It helps that the Swift weighs far less than it looks like it should. At just 100 grams total, the Swift simply doesn’t weigh enough to get thrown off. 


Comfort aside, though, the real beauty of the Swift RL shines through when you actually turn it on. 

Good headlamps offer a variety of brightness settings to match whatever environment you’re running through. 

Great headlamps, though, take that a step further.

Swift RL: RL = Reactive Lighting

Rather than having to click through all those different settings every time you step in or out of the moonlight, the Swift RL takes care of it for you. 

Set it and forget it

  • The brightness will automatically adjust as you go. 
  • If that feature ever gets too overwhelming, switch back to standard mode for a static stream at whatever brightness you choose. 
  • One button controls it all, so you can easily flop between different intensities and widths, from a narrow beam to a broad swath of light. 


The Swift RL truly packs a punch. It reaches up to 900 lumens at peak brightness, which is more than enough to illuminate the darkest trails and secluded roads. 

Battery life

  • Even on the max setting, it lasts up to 2 hours in Standard mode.
  • In Reactive mode, it can last up to 30 hours, when it can ebb and flow to save energy. 
  • At the lower settings, you’ll get 50-100 hours out of the Swift before it needs a recharge. 
  • The five-stage battery indicator will keep you updated on what’s left in the tank. 

Charging the battery

When the time comes, plug it straight into the wall with a micro-USB cord for about six hours until all five give you the green light.

Note: As nice as the rechargeable nature of the Swift is, one downside is that you don’t have the option to swap out normal batteries instead.

But with a little planning, it should last just fine through the longest early morning training runs and overnight ultras. You can also carry an extra Accu Swift battery to swap out as needed.

If you’re looking for something even less in-your-face (literally), then the Iko Core will fit the bill. 

This 79 gram ultralight, ultrathin headlamp looks more like something from a science experiment than a piece of running gear. 

It seems neither comfortable nor practical at first glance. But you won’t regret giving the Iko Core and its goofy exterior a chance. 

No headband. Try this rubberized crown

Missing from the Iko Core is the traditional stretchy headband. 

In its place, Petzl’s opted for a crown-like construction made from rubberized plastic. 

  • The band rests lightly on your head and stays put without needing to be excessively tight.
  • It bends to align with the natural curves of your noggin. 

Note: It takes a few tries to get the fit right. I even discovered that I had it on upside down for the first handful of test runs. But after some trial and error, I don’t have to touch the bungee at all; I just slide it on and it falls right into place. 

More trimmed down features

The band isn’t the only part that Petzl’s trimmed down. 

  • Battery: On the Iko Core, the battery’s been moved to the back. 
  • Lamp size: That leaves the LED lamp free to sit flat against the forehead at a fraction of the regular size. The battery then nestles right under the bone on the back of your skull. It actually feels kind of nice, like a supportive headrest. 
  • Bouncing is the least of your concerns when the lamp is a mere centimeter thick. 


The trade-off for such a minimalist design is a noticeably lower output. 

  • Lumens. The Iko Core reaches up to 500 lumens at its highest setting, and only offers three brightness levels compared to the Swift’s six (if you count both Standard and Reactive modes). 
  • There’s no Reactive Lighting on the Iko Core either, which lowers the overall battery life and requires more attention to your surroundings. 

Charging the battery

On the bright side (forgive me, I had to slip that pun in somewhere), it’s easier to power up the Iko Core than the Swift RL. 

  • You can either recharge the battery in three hours with a micro-USB, replace it with a backup, or use three AAA’s in a pinch. 
  • One charge will get you anywhere from 2 to 100 hours depending on brightness, so carry a spare for peace of mind when the sun sets in the middle of your 100 miler. 

Petzel headlamps: And the winner is...

If I had to choose one for every adventure through the dark, I’d go with the Swift RL.

  • The higher intensity, longer life, and hands-free nature of the Swift sets my mind at the most ease when I’m running alone on my remote local trails. I
  •  know I’ll be doing a fair amount of early-training runs, dawn-patrol ski tours, and alpine start mountain scrambles. 
  • I’ll take a bit more heft if it means feeling more secure out there on unpredictable terrain.

But when it comes to overnight ultramarathons, the Iko Core wins. 

  • It’s so light and compact (especially when folded down into a flat figure-8) that it can fit into any pocket, so it’s not a burden during the day. 
  • The replaceable battery means there’s no cap on how far you can go…or how long it takes to stumble to the finish.

Choose a headlamp to light your way...

To make your own best choice, start with your goals and move backward. 

  • Have a lot of solo runs on the docket like me? Go for power with the Swift RL. 
  • Just need to light your way through race day? Save on space and weight with the Iko Core. 

Either way, you’ve got a way to stay safe and run your best through the dark with these two Petzl headlamps.

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Lucie Hanes
Eagle, CO
8 Following

Ultrarunner, rock climber, occasional artist, fond of good wordplay. Small human on big adventures with big goals and big fee...


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