Axios Finish Line

Three factors determine 80%+ of our longevity — diet, exercise and sleep. Of those, sleep is by far the easiest to get right.

Why it matters: We aren't. 1 in 3 American adults don’t get enough sleep — defined as 7 or more hours a night — per a Centers for Disease Control and Prevention study.

• The average American adult slept 7.9 hours a night in the 1940s. That has dropped to 6.8 hours a night.

The stakes: Over time, operating without enough sleep can dramatically increase your risk of heart disease, stroke and cancer, Francesco Cappuccio, a heart health and sleep expert at the University of Warwick tells us.

• Medical research has linked insufficient sleep to obesity, depression, anxiety, and even heart failure and dementia.
• Lack of sleep also drives up individuals’ costs of health care and companies’ loss of productivity, studies have shown. Employees who aren't getting enough rest are far likelier to be unfocused, miss days of work or get injured on the job.

"Sleep is not a dead state," says Cappuccio. "It's like pressing the 'save' button on a computer."

• Your body is repairing tissue, organizing thoughts and consolidating memory.

We asked the experts to break down good sleep for us.

1. Not all bedtimes are created equal. One of the best ways you can improve your life is to figure out your best hours — are you a night owl, an early bird or somewhere in the middle? Tailor your sleep schedule around that — and keep it consistent.
2. Think about "sleep hygiene." The environment you sleep in affects the health of your sleep. Neat rooms, little light, low noise and set bedtime routines all matter.
3. Soak up the sun. Getting enough Vitamin D and moving around throughout the day will tire you out.
4. Beware sleep’s enemies. Alcohol and caffeine can lower sleep quality when consumed at night. Long naps can cause insomnia (the best power naps are 20 minutes or shorter, experts say).
5. Power down. The light emitted from your devices can roil your circadian rhythm. The National Sleep Foundation recommends ditching screens 30 minutes before bed.

And it's not just about individuals, Cappuccio says. If you're a manager, check in with employees to make sure they have enough time to rest. There's a business case for workers getting sufficient sleep.

The bottom line: We're better parents, friends, neighbors and colleagues when we catch enough zzz.

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Do you dream in color?

• Back in 1942, W.C. Middleton, a DePauw University psychologist, conducted a study of college students. Some 70% reported rarely or never seeing colors in their dreams, and just 10% frequently saw color.
• Eric Schwitzgebel at UC Riverside replicated the research in 2010. In that study, 18% rarely or never saw color and 57% frequently did.

Scientists theorize that the prevalence of color in dreams is tied to the rise of color TV.