How can I handle wake/sleep status automatically?

It might depend on which language your Homey is set to and the wordings Athom chose for that language. In the Dutch language setting the cards actually refer to whether someone went to sleep/woke up, and is or is not sleeping. I think that the intention of those cards is not necessarily that you are actually sleeping, but went to bed with the intention to sleep and hence want flows to do different actions (or suppress actions) compared to when you would be fully awake.

I am also using those states as such. And use additional conditions to determine whether this sleep/awake state should be set.

For example, I am using a car seat presence (pressure) sensors to determine whether I am in bed (on my half of the bed). Homey only sets me to sleep if the senor is triggered in a certain time span: the usual period in which I would go to bed (to sleep) and wake up. Also when pressure is released, Homey sets me to awake if it occurs in the usual time span that I would be awake. When I leave the house, and would somehow still be set to asleep, Homey would set my status to awake.

Of course there will always be incidental cases were I would deviate from my normal routine. Then I can always set my status manually. I don’t think that you can create an automation that is always correct, unless you can determine that you are actually sleeping (in your house).