Day-to-day routines—how we spend our time, care for our bodies and minds—continually shape our moods. Those that build up physical and mental resources can raise mood. Other routines have the potential to seed low mood.

In his thought-provoking new book The Depths: The Evolutionary Origins of the Depression Epidemic,  Jonathan Rottenberg reports that mundane influences like how much sleep and exposure to sunlight we get have a direct impact on mood. “Part of the answer to the riddle of low mood,” says Rottenberg, an Associate Professor of Psychology at the University of South Florida, where he directs the Mood and Emotion Laboratory, “lies in contemporary routines that increasingly feature less light, less rest, and more activities that are out of kilter with the body’s natural rhythm.”

We sleep about two hours less per night than folks did just 100 years ago. And natural daylight? In a recent study, adults in San Diego, one of the sunniest cities in the United States, logged an average of only fifty-eight minutes of sunlight a day. (And, yes, Rottenberg notes, those San Diegans who received less light exposure during their daily routines reported more symptoms of depression.)

An all-too-familiar example of a modern routine almost perversely designed to wreak havoc on the mood system comes in the form of… staring into a brightly glowing screen at night. That’s light stimulation at just the wrong time, which throws off the body’s circadian rhythm as well as making a good night’s sleep less likely. Hello, downward spiral.

There are many factors that contribute to low moods and depression. But there is no harm, and much to be gained, in taking some obvious steps to foster more stable and productive moods. Consider starting here: Put down the phone/tablet/laptop and/or step away from the jumbotron an hour—or two—before bed. And go to bed early enough.

(There are about a bazillion more reasons to sleep well; here are 10. We can talk about diet and exercise another time, ok?)

Now I can hear some of you grumbling some variation of “Yeah, that sounds nice. Just. Not. Possible.” And I get it, I really do. I’ve been there, myself. The thing is, it is possible, even though it doesn’t look that way from where you’re standing right now. Which means that the leverage point we’re looking for is not so much about time management as it is about shifting your point of view to one where a good night’s sleep is not only possible, it becomes a foundation for a world of positive change.

Doesn’t the very thought of that lift your spirits?