"Guard your sleep like it's your best friend . . . because it is," Carla Manly, PhD, a practicing clinical psychologist and stress expert, told POPSUGAR. A lack of proper sleep can increase your stress levels, so it's important to make sure you're getting enough of it. "To protect your sleep, go to bed at a set time each evening, lower lighting levels a few hours before sleep, avoid caffeine and sugar after 3 p.m., and keep technology out of your bedroom," she said.