Is it an invasion of privacy to use an app that tracks what time a person sleeps?

Question

Anonymity

If it uses only legal data sources - the history of calls, sms, letters, social. networks and instant messengers, including information open only to friends/contacts. That is, in fact, the application simply looks when a person is active, and if there is a lot of information about it during the period of wakefulness, then with a good probability it predicts the time of sleep and the general mode.
The person did not explicitly agree to track his sleep time, but he did not forbid it either.

Answer 1

history of calls, sms, letters, social. networks and messengers

I will never install such an application.

the application just looks when a person is active

Does it mean that I do not let go of the phone? I came home, threw the phone on the sofa, sat down at the computer and plunged into the game, from which I "surfaced" after six hours. Am I sleeping at this time or not? :)

Answer 2

legal data sources - the history of calls, sms, letters, social. networks and messengers

Where are these legal sources?
Not related to personal information.
If he gave access to certain sensors, then this is no longer important.