Of the many good things about spring, about now is when the lightening sky starts providing useful cues for waking up. If it’s still dark, I don’t need to check the time and can just go back to sleep. And if it’s getting light outside, it’s time to get up.
From 11:56 AM until 12:12 PM today, the sun will be high enough in the sky that its powerful actinic rays will reach the earth with enough energy for exposed skin to produce vitamin D.
Of course, the temperature around noon will be about 12℉, so I’m not expecting to have much exposed skin, but it is still nice to know that vitamin D production will be possible.
There might be an unseasonably warm and sunny day at any time this month or next, giving me a chance to make some vitamin D. And soon enough spring will come.
(Ephemeris data valid for where I live. The opening of the vitamin D window will likely be different for you.)
I shared a link to this article by Rowan Jacobsen, with the comment “This article falls so squarely in the sweet spot of reinforcing my own preconceptions, I almost hesitate to tweet it.” But I did, with a few brief quotes.
Freed of the limitations of twitter, here’s a more extended excerpt:
Lindqvist tracked the sunbathing habits of nearly 30,000 women in Sweden over 20 years. Originally, he was studying blood clots, which he found occurred less frequently in women who spent more time in the sun—and less frequently during the summer. Lindqvist looked at diabetes next. Sure enough, the sun worshippers had much lower rates. Melanoma? True, the sun worshippers had a higher incidence of it—but they were eight times less likely to die from it.
So Lindqvist decided to look at overall mortality rates, and the results were shocking. Over the 20 years of the study, sun avoiders were twice as likely to die as sun worshippers.
There are not many daily lifestyle choices that double your risk of dying. In a 2016 study published in the Journal of Internal Medicine, Lindqvist’s team put it in perspective: “Avoidance of sun exposure is a risk factor of a similar magnitude as smoking, in terms of life expectancy.”
Jacobsen later mentions the app dminder, which I’ve been using for several years now. It helps you optimize your sun exposure (getting maximum vitamin D production without getting sunburned, based on time of year, time of day, location, and skin pigmentation). I just checked the app, which tells me that it’s just 8 days until the vitamin D window reopens here in Savoy, Illinois!
I concluded my little tweet storm with this: Pretty much every nice day of the spring, summer, and fall, I announce to my wife around midday that “I’m going out to expose my integument to the deadly actinic rays of the sun.” And then I do. I feel so much better since I started doing this.
At 5:30 AM, as Jackie heads to work, the sun has not yet risen. It won’t rise until 5:39 today. Worse, the encroaching darkness is speeding up: It won’t rise until 5:45 a week from today.
I have always enjoyed exercising in the heat. In this I seem to be different from most people.
I originally took note of this fondness back in the early 1980s when I was living in Ft. Lauderdale. A ritzy local tennis club—way too expensive for me—offered summer memberships for just $100. I just got access to the outdoor courts and not to the indoor amenities, but all I wanted was a place where I could reserve a court and know that it would be available when I met someone there. The only downside was that you were playing tennis outdoors, in the summer, in Ft. Lauderdale. And it turned out I was okay with that.
I’m pretty careful not to be stupid about it. (And successfully so, it seems—I’ve never gotten heat exhaustion or heat stroke.) If I start feeling tired, thirsty, or overheated, I slow down, move to the shade, and drink some cold water.
Over the years I’ve had a variety of theories about why I didn’t mind exercising in the heat when other people hate it so much. I like to imagine that I’m just better at tolerating the heat than the average person: Everyone slows down in the heat, but maybe I slow down slightly less; at some high temperature, maybe I’d become competitive! More likely, since I’m not competitive I’m not making unfavorable comparisons between my speed in the heat versus my speed in cool weather, so the fact that I slow down doesn’t make me unhappy.
Recent research has given me a new, much more likely reason why I like exercising in the heat. On Rhonda Patrick’s Found My Fitness podcast, I heard an interview with Dr. Charles Raison, in which he described the results of a study suggesting that Whole-Body Hyperthermia was an effective treatment for depression. The experiment used infrared lights to heat people up to a core body temperature of 38.5℃ (101.3℉), but Raison is convinced that there is nothing special about the device used, and that a sauna, hot spring, sweat lodge, hot yoga—or just exercising in the heat—would have the same antidepressant effect.
Dr. Raison is studying further to try to elucidate the mechanism by which hyperthermia boosts mood in depressed people. (It seems to reduce inflammation, perhaps by boosting IL-6 which activates IL-10. Heat Shock Proteins might also be involved, since they do all sorts of things.)
I have always been inclined to blame a lack of daylight for the seasonal depression that I’m prone to suffer from during the winter—both too short of a photo-period (which I address with a HappyLight™) and too little vitamin D (which I address with vitamin D supplements), but it now occurs to me that a lack of opportunity to exercise in the heat (and thereby raise my core body temperature high enough to trigger whatever it is that reduces depression) may be an independent factor.
It seems very likely that, just like my desire to spend time outdoors in daylight is probably self-medicating to boost my vitamin D and regulate my circadian rhythm, my desire to exercise in the heat is probably self-medicating to boost my mood.
I hesitate to rejoin a fitness center just to get access to a sauna, but I’ll have to investigate options for access to winter whole-body hyperthermia.
Watching the sunrise out my study window.
Thanks to yesterday’s preternaturally warm weather I was able to expose enough skin to the deadly ultraviolet ray of the sun as to make a non-trivial quantity of vitamin D. (Plus, get in a very nice walk at the River Bend Forest Preserve.)
Some time in October every year I quit being able to get enough sun to make my own vitamin D. Eventually it gets too chilly to go out with enough skin exposed, and even if it stays warm late into the fall, eventually the implacable reality of the earth’s axial tilt means there simply aren’t enough minutes of the day when the appropriate frequencies of UV light shine down where I live.
As a practical matter, this period runs about six months. By early March there’s probably enough UV available, but it’s usually early April before the stars align such that we can take full advantage. We need days when it gets warm fairly early, because the UV is only available for a few hours right around solar noon. (Warmth at 3:00 PM is great, but doesn’t help with the UV until later in the year when the sun is even higher.) We need to get at least two or three of those days each week. (Just two days would probably be enough, if one never had schedule conflicts that kept one out of the sun around solar noon.)
My experience has been this all works out to mean that I need to rely on supplements for my vitamin D needs for right around 180 days per year. With that in mind, I’ve taken to buying two 90-pill bottles of vitamin D each fall.
When I notice—as I say, usually sometime in October—that it has been several days since I managed to get enough sun, I start taking the pills.
Just a few days ago, I finished my first bottle and opened my second.
That means I’ve made it halfway through! Another 85 or 87 days and I’ll be done with the pills and able to make my own vitamin D!
The last few years I was taking 1000 IU pills. This year I upped it to 2000 IU each day. (Not quite as big a change it sounds—I used to eat a lot of children’s breakfast cereals, often supplemented with vitamin D, but since I went low-carb I’m eating a lot less of those.)
It’s still a somewhat higher dose, which I think may be helping. So far this year I’ve only had a couple of days when I found myself glum for no good reason, a bit better than average, I think.
Steven always warns me against imagining that spring starts before April. But soon—less than 90 days now—I’ll once again be able to make my own vitamin D.
Today is the last day this season that sunrise (where I live) is later than 7:15:00 AM.