[Expez]

You are complecting two problems: 1) When does the other person sleep. 2) What does his watch show.

Making 2) easier does not change anything with regard to 1).

[philwelch]

For most people, their sleep is highly correlated with what their watches show.

[fvirexi]

It doesn't change the sleep patterns, but would you say it does not make a difference in judging at which hours other people sleep?