The extension of afternoon-daylight hours does us no favors when it begins in the spring. Its accompanying loss of an hour of sleep can lead to alertness problems and, as a result, accidents. Here's a new study from Medical News Today explaining that effect.

And its end has little to do with seasonal-affective disorder or winter blues or whatever you choose to call that annual fall mood decline. Take a read of this L.A. Times story from the spring of 2007, when the current expansion of daylight saving time began.

It notes that the extension, which was supposed to give people extra light later in the day, can actually make them feel less sunny. As one expert on biological rhythms says in the story: "It's the early morning light exposure that allays the symptoms of winter depression. The later the sun rises, the more likely we are to get depressed."

That's not to say you're not affected by the dwindling amounts of daylight.