The Happiness Project: Or, Why I Spent a Year Trying to Sing in the Morning, Clean My Closets, Fight Right, Read Aristotle, and Generally Have More Fun

got enough sleep and enough exercise. Although I’d already known that sleep and exercise were important to good health, I’d been surprised to learn that happiness—which can seem like a complex, lofty, and intangible goal—was quite influenced by these straightforward habits. For my mental energy: I needed to tackle my apartment and office, which felt oppressively messy and crowded. Outer order, I hoped, would bring inner peace. What’s more, I needed to clear away metaphorical clutter; I wanted to cross tasks off my to-do list. I added one last resolution that combined the mental and the physical. Studies show that by acting as if you feel more energetic, you can become more energetic. I was skeptical, but it seemed worth a try.
    GO TO SLEEP EARLIER.
    First: bodily energy.
    A glamorous friend with a tendency to make sweeping pronouncements had told me that “Sleep is the new sex,” and I’d recently been at adinner party where each person at the table detailed the best nap he or she had ever had, in lascivious detail, while everyone moaned in appreciation.
    Millions of people fail to get the recommended seven to eight hours of sleep a night, and one study revealed that along with tight work deadlines, a bad night’s sleep was one of the top two factors that upset people’s daily moods. Another study suggested that getting one extra hour of sleep each night would do more for a person’s daily happiness than getting a $60,000 raise. Nevertheless, the average adult sleeps only 6.9 hours during the week, and 7.9 on the weekend—20 percent less than in 1900. Although people adjust to feeling sleepy, sleep deprivation impairs memory, weakens the immune system, slows metabolism, and might, some studies suggest, foster weight gain.
    My new, not-exactly-startling resolution for getting more sleep was to turn off the light. Too often I stayed up to read, answer e-mails, watch TV, pay bills, or whatever, instead of going to bed.
    Nevertheless, just a few days into the happiness project, although I practically fell asleep on Eliza’s purple sheets as I was tucking her in, I wavered for a moment when Jamie proposed watching our latest Netflix DVD, The Conversation. I love movies; I wanted to spend time with Jamie; 9:30 P.M . seemed a ridiculously early hour to go to bed; and I knew from experience that if I started watching, I’d perk up. On the other hand, I felt exhausted.
    Why does it often seem more tiring to go to bed than to stay up? Inertia, I suppose. Plus there’s the prebed work of taking out my contact lenses, brushing my teeth, and washing my face. But I’d made my resolution, so resolutely I headed to bed. I slept eight solid hours and woke up an hour early, at 5:30 A.M ., so in addition to getting a good night’s sleep, I had the chance to do a peaceful block of work while my family was still in bed.
    I’m a real know-it-all, so I was pleased when my sister called and complained of insomnia. Elizabeth is five years younger than I am, but usually I’m the one asking her for advice.
    “I’m not getting any sleep,” she said. “I’ve already given up caffeine. What else can I do?”
    “Lots of things,” I said, prepared to rattle off the tips that I’d uncovered in my research. “Near your bedtime, don’t do any work that requires alert thinking. Keep your bedroom slightly chilly. Do a few prebed stretches. Also—this is important—because light confuses the body’s circadian clock, keep the lights low around bedtime, say, if you go to the bathroom. Also, make sure your room is very dark when the lights are out. Like a hotel room.”
    “Do you really think it can make a difference?” she asked.
    “All the studies say that it does.”
    I’d tried all these steps myself, and I’d found the last one—keeping our bedroom dark—surprisingly difficult to accomplish.
    “What are you doing?” Jamie had asked one night when he caught me rearranging various devices throughout our room.
    “I’m trying to block the light from all these gizmos,” I answered. “I read that even a tiny light from a digital alarm clock can disrupt a sleep cycle, and it’s like a mad scientist’s lab in here. Our BlackBerrys, the computer, the cable box—everything blinks or glows bright green.”
    “Huh” was all he said, but he did help me move some things on the nightstand to block the light coming from our alarm clock.
    These changes did seem to make falling asleep easier. But I often lost sleep