I first started running twice a day as part of my training for the Burning River 100 Mile Endurance Run last summer. Before, after a long exhausting run, I would never have considered even walking very far on the same day. In fact, until I started running barefoot, I would always take a day off after my weekly one long run. But running barefoot allowed my body to recover faster, and actually puts less wear and tear on my legs in general, so I could easily, and gladly, run every day.
And for Burning River, I simply had to run more—a lot—like, lots o' hours and miles a week in order to get anywhere close to what I'd be doing in that race. At the beginning of the summer I was doing long runs every other day, and on the odd days, doing a shorter run of an hour (or two), allowed me some recovery time, enough to have energy for the rest of the day. So, with that energy there, I decided to go out for short mellow runs at night. And, that was possible, and in fact not unpleasant at all.
So, I started to do a nightly run, no matter how far I'd gone in the morning. Sometimes it was funny, a little absurd almost, to trudge out at nine o'clock, my legs sore sore, but curiously having energy, so I had discovered that soreness and tiredness are two different animals. And, once I started trudging, the legs would loosen up, and some of the soreness would go away. Just to experiment, for the sheer audacity of it, I even tried doing a short run the night that I had run a marathon. I went slow (that was the only way I could go), but I went.
The second run also helped if I just couldn't run very long in the morning, because of work or travel or whatever. So, If I could only run a half-hour, or hour, in the morning, adding on a half hour at night made me feel better about keeping up some sort of decent schedule for the Big Race. I actually started to boost the length of my night runs because they just felt good.
The only sacrifice I really made in adding night runs was cutting into my reading time. I usually like to read an hour or more before going to sleep, but it was a sacrifice I was willing to make, and as a teacher, I had the summer off, mercifully, so I read enough during the day. I don't own a t.v. (again, mercifully) and I can't imagine not watching one as any kind of sacrifice. I was also living in a town where I didn't know a lot of people, was single, and didn't have too much of a social life. How any endurance runner can be married, much less have a family, I'm still not sure.
I did and do not run barefoot at night. Even though I'm mostly running in semi-lit areas, I just do not want to risk stepping on a piece of glass, or just any pokey thing. Instead I usually wear my Luna huaraches by Barefoot Ted and crew, even in Winter. I'll put on a pair of Injinji socks to keep the feets warm. If it's wet and/or slushy, I'll maybe wear my VFFs.
I actually grew really fond of my night runs. I know some people run at night normally, but I prefer to do my runs first thing in the morning, to start my day active, but running at night, especially since I treated them as 'treats,' with no desire to push myself time or effort-wise, just a light trot, are peaceful. It's dark (in the city, I don't feel the need to wear a headlamp—hate those things anyways) and quiet, little traffic, few people period. Cool air. Very solitary and contemplative. Looking into houses, seeing people sitting in front of the idiot boxes, eating Doritos and watching Dancing With The Stars, I admit to a feeling of healthy smugness, though feeling bad too that that's what people consider 'normal' now, and wishing they would just get out and walk at least.
Even now, after the race (months after really), I still enjoy a second run in the evening. Not all the time this Winter, since I am after all Michigan, and hate the cold, but though running raises my heart rate and gets my blood pumping, it doesn't keep me up at night, and in fact relaxes me, de-stresses me, helps me sleep better.
As the next summer approaches, and Michigan warms up, I'm not sure if I'll be able to train for another 100 miler or not. It's a lot of work and time, and I'll be moving, changing jobs. But with warmer weather, a second run in the day is now almost part of my regular routine, to the point where I consider it almost a ritual.