Even though I usually refrain from observing four-twenty, it gets a whole lot lamer when it’s dark out. The Boston sun will bid us a dismally premature farewell—setting prior to 4:20 p.m.—from this week through late December, leaving us indebted to Thomas Edison for practically everything we do. The perpetual darkness of early winter may be a drag, but probably more irritating and monotonous is the industrial scale on which we complain about its inconvenience. Restoring year-round Daylight Saving Time could silence that unpalatable grumbling. But the real reason to take this measure is neither to generate less prosaic conversation topics nor to smoke pot amidst the splendor of natural sunlight. Our yearly hiatus from Daylight Saving Time has consequences far—ahem—darker than these.

Daylight Saving Time saves energy. That’s why we have it. Most consumers of energy waste daylight by waking up after sunrise and going to bed after sunset; for seven months of the year, Daylight Saving Time recovers an hour of this wasted daylight and allows us to use the sun for an additional hour in the evening, free of charge. For the other five months, it’s a different story. To the delight of petroleum exporters, we burn large quantities of oil to power the light bulbs that keep this country’s homes and businesses running for many hours after sunset in the winter. What can we do to keep the air a little cleaner and our deficits a little lighter? A 2001 study by the California Energy Commission showed that observing Daylight Saving Time year round would cut winter electricity use at peak times by 3.4 percent—a really impressive statistic because it is limited by fixed electricity uses such as running household appliances. The modest amounts of energy conserved by setting clocks forward add up in the long run.

But the burdens of life without daylight are in many cases personal. Six percent of Americans suffer from Seasonal Affective Disorder (SAD) each winter, and an additional 14 percent experience more minor daylight-related mental health problems. SAD is eminently threatening at Harvard, where late bedtimes and heavy workloads conspire to deprive students of natural light. Extending Daylight Saving Time through the winter would alleviate an ample share of such cases.

An even more compelling reason to keep sunlight on the post meridiem end of the day, though, is physical safety. The Department of Transportation found that in March and April of 1974 and 1975, when observance of Daylight Saving Time was lengthened as a response to the oil crisis, 50 lives were saved, 2000 injuries prevented, and $28 million saved in avoided traffic accidents. While the early part of the morning commute might have been a shade darker, travel home from work and became much safer for taking place earlier with respect to sunset—including at Harvard where sexual assault and other crimes are far more likely after dark.

As we longingly await the return of longer days we shouldn’t overlook the oft-unnoticed toll that gloom takes on us, physically and mentally, as individuals and as a society. But it doesn’t have to be this way—if we save daylight when it’s abundant, why not do the same when it’s scarce? We can’t afford to stay in the dark.

—Daniel B. Holoch is an editorial editor.