The masses have spoken, and evening runs (between 6 and 7 p.m. specifically) are the most popular. During the summer, this timing makes sense, as the sun sets later and hopefully some of the day's heat and humidity have waned by then. But, now that we're beyond Daylight Savings Time, the sun is setting long before work ends, and the temperature is dropping quickly.
Outdoor running and biking at night come with a slightly different set of rules than their daytime brethren — especially when it comes to clothes. Now, neon isn’t just a fashion choice; it’s a safety essential. To be spotted by drivers and other athletes alike, you need to think reflectivity, neon, glow-in-the-dark, and lighted accessories. And, with the growing popularity of nighttime-themed raves-cum-races such as the Electric Run, brands have met this increasing demand for visibility-enhancing gear, so you have more options, beyond the basic head lamp and crossing-guard vest.
The other key element to running safely at night is to think numbers, location, and alerts. That means carrying some sort of identification with you (such as an ID band), wrangling friends to join you, or heading out with a run-club group. You may want to look into using worst-case-scenario apps (including the web-based services Kitestring and Hiker Alert) that tell your emergency contacts if you don’t check in within the time you allotted for making it home safely. Also, stick to busy roads, pre-plan your route, stay alert, and keep your music volume low (if you can't work out sans tunes), so you can be aware of your surroundings.