Feeling exhausted? You're not alone.

Thirty-five percent of American adults get less than seven hours of sleep a night—seven to nine hours are recommended each night—while 50-70 million adults are currently diagnosed with a sleep disorder, according to the American Sleep Association.

While there are a number of factors that contribute to this, that afternoon coffee you're currently sipping could have something to do with it.

"What you put in your body can heavily affect your sleep," explains .

Caffeine works by changing the chemistry of the brain, thus, blocking the action of adenosine, a natural brain chemical associated with sleep.

"How caffeine affects you is a bit genetic," Dr. Rochford says, noting "You know, some people can drink espresso after dinner and fall asleep three seconds later."

However, for most of us, a coffee late in the afternoon can have a significant impact on our ability to fall asleep and get a restful night.

"You can potentially get away with a coffee in the afternoon, probably at the latest, 1 p.m. to 2 p.m.," says Dr. Rochford. However, if you have real trouble sleeping or are highly sensitive to caffeine, it's even earlier. "You've got to have your own barometer, but the general rule is not after lunch."

LISTEN: Robin Bailey shares her trick to getting more sleep on The Well, from our Australian sister site Mamamia's podcast network. (Post continues below.)

Organizations like the American Sleep Association and the National Sleep Foundation are encouraging people to make better choices when it comes to sleep, like heading to bed an hour earlier.

"If you're not getting enough sleep, I think one more hour will encourage people to focus on getting more sleep," says Dr. Rochford. "We cram everything into our days and nights and on the days when we then binge Netflix until 2 a.m., that's the moment when one hour sleep is much more needed."

Added Dr. Rochrod, "It's about people starting to recognize that you need to place the same kind of emphasis on sleep as you do other health-related habits, such as food or exercise."

This post originally appeared on Mamamia, Spring.St's Australian sister site. You can read it here.