A monitoring system for monitoring human activities, comprising a multiple number of presence detection sensors (2a-e) mounted in a residence, further comprising a control unit communicately connected to the presence detection sensors (2a-e) and arranged for receiving presence data from the presence detection sensors (2a-e), wherein the control unit further is arranged for determining, from the received presence data, whether the inhabitant of the residence stays indoors or outdoors and for determining a time interval of an outdoor stay, characterized in that the presence detection sensors (2a-e) include a single or a multiple number of door sensors, wherein the control unit is further arranged for counting a number of outdoor stays having a time interval that is longer than a predetermined threshold time period, wherein the control unit is arranged for determining that the inhabitant of the residence stays outdoors by detecting that a front door has opened and closed and that, after the door has closed, no activities have been detected anymore, wherein the control units is arranged for determining that the inhabitant enters the residence, and is thus indoors, by detecting that the front door has opened and closed, after an outdoor time period, and activities of the user indoors are sensed, wherein the control unit is further arranged for counting a number of home visits, by non-inhabitant visitors, in the residence of the inhabitant by comparing detection data of the front door being opened and closed with multiple simultaneous activities sensed in the residence, wherein the control unit is arranged for determining a social interaction indicator based on a total number of counted outdoor stays and/or counted home visits in an evaluation time period, and wherein the control unit is also arranged for sending an information signal to a software platform informing relatives and/or professional caregivers, based on the determined social interaction indicator or on a time dependent evolution of the determined social interaction indicator. wherein the control unit is further arranged for counting a number of outdoor stays having a time interval that is longer than a predetermined threshold time period, wherein the control unit is arranged for determining that the inhabitant of the residence stays outdoors by detecting that a front door has opened and closed and that, after the door has closed, no activities have been detected anymore, wherein the control units is arranged for determining that the inhabitant enters the residence, and is thus indoors, by detecting that the front door has opened and closed, after an outdoor time period, and activities of the user indoors are sensed, wherein the control unit is further arranged for counting a number of home visits, by non-inhabitant visitors, in the residence of the inhabitant by comparing detection data of the front door being opened and closed with multiple simultaneous activities sensed in the residence, wherein the control unit is arranged for determining a social interaction indicator based on a total number of counted outdoor stays and/or counted home visits in an evaluation time period, and wherein the control unit is also arranged for sending an information signal to a software platform informing relatives and/or professional caregivers, based on the determined social interaction indicator or on a time dependent evolution of the determined social interaction indicator.