“Appetite is tied to sleep,” Avidan says. When you sleep, the cells in your brain may shrink, allowing the cerebrospinal fluid to wash away the built-up waste. If you don't sleep, your brain isn't receiving the \"cleaning\" it needs—and the consequences might be dire. Some of the most common sleep disorders are sleep apnea, chronic insomnia, and restless leg syndrome; these can be treated by a medical professional. Avoid longer naps, as you’ll likely wake up during a deep sleep or REM sleep and feel groggier and more confused.