Sleep is your body’s way of repairing itself and running like a well-oiled machine. It’s not so much an act of entertainment as a tool for your brain as a whole.

“Sleep cleanses toxins and wastes that accumulate during the day. It also refines neural connections and prioritizes the ones we use frequently (as well as new information),” explains Major Allison Brager, Ph.D., a neuroscientist in the US Army. A holistic health and fitness system specializing in sleep.

Sleep is also vital for restoring your physical and nervous energy, Brager notes, and gives the neural clusters that make up our nervous system a chance to go “offline” in turns. In other words, poor sleep can Affect all of your mental faculties, affecting how you feel and perform both mentally and physically.

That being said, board-certified sleep specialist Michael J. Breus, Ph.D., affectionately known as “The Sleep Doctor,” tells mbg that it takes more than one night of Bad Sleep to significantly affect the quality of your life. However, it can affect your mood and productivity the next day. Here are some expert-approved tips for dealing with lingering sleepiness.