You can hide it from everyone around you, but your phone knows when you are upset and can even detect you depression.
According to a research conducted by the Northwestern University, depression can be detected from smartphone sensor data by tracking the number of minutes a person uses the phone and his daily geographical locations.
The research claims that the more time a person spends on his phone, the more depressed he is, as the average daily usage for depressed individuals is about 68 minutes, while for non-depressed individuals, it is about 17 minutes.
Author David Mohr said that the significance of this study is that now they can detect if a person has symptoms of depression and the severity of those symptoms without asking any questions.
Mohr added that the data showing that depressed people tended not to go many places reflects the loss of motivation seen in depression as when people are depressed, they tend to withdraw and don't have the motivation or energy to go out and do things.
The researchers claim that this information can be used to monitor people who are at risk of depression to, perhaps, offer them interventions if the sensor detected depression or to deliver the information to their clinicians.
The research is published in the Journal of Medical Internet Research.