Imagine this: you have a lunch meeting scheduled for noon. You want to impress your client so you choose your favorite restaurant in town -- the brazilian steakhouse downtown. You meet, share some small talk, and tell him to order whatever he wants off the menu. In an effort to impress your client, you tell the waitress to bring the most popular appetizers on the menu for the table. After multiple rounds of lamb, steak, chicken, and the seafood you didn’t even want but ate anyway to justify $200 you just dropped, you both waddle out of the restaurant uncomfortably full.

Question: Do you plug your iphone up every night before you go to sleep? 

I hope you answered yes, because we all know a dead phone offers nothing to us in return. 

One of the highest functioning handheld devices is rendered absolutely useless if it is not charged. 

In the exact same way, your body has a finite amount of battery power each day. If it is not recharged, you are starting the next day at a deficit, and can run out far sooner as the day progresses.