If some humans can handle lactose and others can’t. Some suffer from migraines whilst others don’t etc. you don’t think it’s possible that we also have different circadian rhythms.
Perhaps you could exercise some critical thought. Maybe go read any of the various studies on sleep and make an informed decision rather than a knee jerk reaction.
Also, positive intent. Just assume people are being truthful for the most part. Life is easier if you’re not looking to shit on people.