Timestamps yes, but you can't represent meaningful future times that way.
You should also record the timezone with the timestamp, though. An epoch-time integer will unambiguously tell you what time something was recorded at, but it can't tell you what the time on the clock was at that time. If you're doing some kind of data analysis on user habits, for example, you almost certainly want to work with user local times, not UTC.
You should also record the timezone with the timestamp, though. An epoch-time integer will unambiguously tell you what time something was recorded at, but it can't tell you what the time on the clock was at that time. If you're doing some kind of data analysis on user habits, for example, you almost certainly want to work with user local times, not UTC.