Nocturnal Running and Weight Gain

Some time back – maybe while I was researching my posts on sleep issues or on heart problems related to distance running – I came across research suggesting that people who slept fewer hours at night – or maybe it was people who slept in the daytime – tended to have more problems with gaining weight. The suggestion at the time, as I recall, was that maybe they were more inclined to snack, late at night.

That could be. But an article in Popular Mechanics (Leman, 2022) cites a study by Mason et al. (PNAS, 2022), investigating the effects of ambient light during one’s sleep. Northwestern University (Paul, 2022) elaborates on that study, explaining that human physiology responds to light at night as it does in daytime:

[L]ight exposure during daytime increases heart rate via activation of the sympathetic nervous system, which kicks your heart into high gear and heightens alertness to meet the challenges of the day. …

Investigators found insulin resistance occurred the morning after people slept in a light room. Insulin resistance is when cells in your muscles, fat and live don’t respond well to insulin and can’t use glucose from your blood for energy. To make up for it, your pancreas makes more insulin. Over time, your blood sugar goes up.

An earlier study published in JAMA Internal Medicine looked at a large population of healthy people who had exposure to light during sleep. They were more overweight and obese ….

The study tested the effect of sleeping with 100 lux (moderate light) compared to 3 lux (dim light) in participants over a single night. …

Tips to reduce light during sleep

Don’t turn lights on. If you need to have a light on (which older adults may want for safety), make it a dim light that is closer to the floor.
Color is important. Amber or a red/orange light is less stimulating for the brain. Don’t use white or blue light and keep it far away from the sleeping person.
Blackout shades or eye masks are good if you can’t control the outdoor light. Move your bed so the outdoor light isn’t shining on your face.

According to Wikipedia (see ScopeCalc), the 3 lux level tested in that study would be similar to the brightness outdoors at the dark limit of civil twilight – that is, when you can just barely see outdoor objects clearly enough to get by without artificial lighting, roughly a half-hour before sunrise or a half-hour after sunset (in a location without light pollution).

The 100 lux level would be comparable to a very dark overcast day, or a little brighter than an office building hallway. Paul (2022) seemed to feel that a TV screen (or, presumably, a computer monitor) would be bright enough to have such effects. Again quoting one of the study authors, “If you’re able to see things really well, it’s probably too light.” Popular Mechanics (Leman, 2022) suggested using a night light rather than a lamp, and arranging things so that no lights are directly visible from the bed.

My thought, upon reading these materials, was that sleeping with too much light – due to either lights in the room or daytime sleeping without blackout curtains – could stimulate weight gain, regardless of snacking, because of the physiological effects of exposure to light. To me, as a person who runs at night during the hot months, and who feels moreover that his metabolism has changed within the past few years, this research did support the common-sense conclusion that I should make sure the bedroom stays dark during sleep hours.

Backpack for Running

A few years back, I did a search for backpacks for runners.  I read a number of discussions on the subject, and then narrowed it down.  Since there are hundreds of models, I excluded packs with a wide hipbelt, women’s packs, packs over 30 liters, and packs over $100.  I eliminated heavy packs; the ones listed below are all in the one-pound range.  I eliminated most packs without at least a thin waist or tummy belt, on the theory that a load of stuff could swing around otherwise.  (I was not yet sure how much stuff I would ever want to carry while running, but decided to keep my options open.)  I tended to favor packs that someone – in the ad itself or elsewhere – described as a runner’s pack.  I searched out the Amazon.com listings for each pack, in hopes that this would give me more of a consumer’s perspective.

I eliminated most hydration packs, though possibly they would be fine with the bladder removed.   If I had needed to broaden my search to include hydration packs, I probably would have chosen either a CamelBak or a Salomon.  I also eliminated climbing packs.  The drawback of a typical climbing pack, for my purposes, was its lack of pockets to reach into while running. But I did consider these:

Black Diamond Flash
Black Diamond Bullet
Black Diamond Hollowpoint

I considered two Lowe Alpine packs, primarily when I was thinking I might want to carry a lot of stuff.  I rejected them because I had read several positive remarks by runners who had used Deuter Speed Lite packs.  I had already decided that Deuter would be the kind I would buy.  The two Lowe Alpine packs were:

Lowe Alpine Edge 20 Day Pack
Lowe Alpine Argon 25 Day Pack

The two Deuter choices were:

Deuter Speed Lite 10 Daypack
Deuter Speed Lite 20 Backpack

Between the two, the larger 20 still seemed suitable for running.  It would also hold more.  That would mean more fabric on my hot and sweaty back, but would also extend the tummy strap somewhat lower.  Its dimensions were only slightly larger:  19 x 10 x 7 inches, as compared to 16 x 9 x 5 inches for the smaller 10 Daypack, and presumably not all of that extra length and width would be against my back.  The manufacturer’s webpage showed its straps, with padding down most of the shoulder (a principal disadvantage of the cheap pack I was planning to replace).  The pockets looked a bit high, but accessible if I loosened or unclipped their water-bottle straps.  The other drawback of the larger pack was that it cost $20 more.

I wound up buying the Deuter 20.  I had it for a year or two.  It was a really nice pack.  I sold it just because I wasn’t likely to use it much in my new location.

I never did get around to camp running.  But I did try it out fully loaded and with additional gear bungee-corded to the outside of it, and it worked.  I was impressed with how well I could get it to lie snug up against me, not swinging around and yet not choking me with inconvenient tight straps across the chest.  Somehow it just fit.  I used it for hauling groceries from a store one mile away — carrying, for example, a gallon of milk along with a random load of other items.

* * * * *

Update (January 2023)

I recently tried a distance run with a loaded backpack. It wasn’t one of the models listed here – it was just a basic Outdoor Products pack from Walmart – but I was able to keep it from swinging around. It seemed to provide approximately the experience that I would expect from one of the packs listed above.

Things were fine for a while. Unfortunately, the route I used began with several miles of slight but mostly steady downhill. I had run this route many times before. The grade was slight enough not to cause problems. With the pack, however, problems did ensue.

About four miles out, I got a sudden, stabbing calf pain. I had to walk the rest of the way. As discussed in another post, downhill running was a prime cause of these calf pains.

As with those many previous runs, there was no such attack in a later run on that same route without a pack. It seemed clear that the pack was the cause.

What was less clear was exactly why. I did not think it was the weight. The pack did weigh about nine pounds, so that was possible. It also could have been that the pack induced a change in my running motion – though I think that would have manifested, first, in a joint (e.g., knee) ache.

My best guess was that the problem lay in the slower pace. I definitely was running slower with that weight on my back. I had noticed, in the past, that sprinting down hills tended to minimize calf attacks. I suspect there would not have been a problem on a more mixed route, as distinct from that steady downhill grade. If this was the explanation, a solution might be to walk on the downhill segments, continuously or at least at intervals, or to try to speed up on those segments despite the weight.