I don't know exactly how it works, but I am pretty sure work regulations in Germany also apply to business owners.

Specially insurances will not be covering certain work related diseases with that type of workload.

It has been a continuous discussion in the press in the last years, to the point some companies started enforcing a "go home" policy.

For example, sorry in German,

http://www.spiegel.de/karriere/berufsleben/erreichbar-nach-d...