A new app has hit the headlines recently as the first smartphone application to monitor a person's sleep and then provide them with free specially tailored expert advice to help them make the most of the time they spend in bed. While users won't need to part with any cash, they will need to accept their phones as guest bed sharers before they can find out how to improve their sleep. The Sleep101 app, which was created by Zeo, works by tracking a person's movement throughout the night, so the phone needs to be placed on the bed. It boasts 86.2 per cent accuracy as wrist actigraphy, which is the clinically proven way to monitor sleep using wrist movement. However, users who share a double bed with a partner may experience difficulty achieving accurate results as the other person's movement may interfere with the tracking process. After tracking how long and how well a person slept, the app allows users to join a seven-step Sleep Better Challenge and to read expert sleep advice to help them in the future.