Help4Mood is a closed loop approach supporting the control, communication and treatment management of patients with Major Depression. The first out of the three main components of the Help4Mood solution is the Personal Monitoring System (PMS), a set of different wireless sensors whose data sink is centralized on a laptop. The objective of this PMS is to monitor the activity of the patients, so several sensors have been chosen to cover the needs of different individuals. These include a wrist watch, a key ring, a waist/belt sensor, an under mattress sensor and a cellular phone. This paper describes the first prototype and the results obtained from this Wireless Sensor Network.