If you want to sleep better at night, then change your diet. People who eat less fiber and more saturated fat and sugar are far more likely to experience lighter, less restorative and more disruptive sleep, according to researchers from Columbia University Medical Center in New York City. And the opposite is also true. Those whose diets have a greater amount of fiber, higher protein and less saturated fat and sugar, are able to fall asleep faster and spend more time in the stage of deep, slow wave sleep. Specifically, saturated fat is responsible for less slow wave sleep, while sugar is associated with more arousals from sleep. And here’s the most astonishing finding: A single day of greater fat intake and lower fiber is enough to disrupt sleep that night.