Heating at night: should it be switched off or simply turned down?

Conclusion: The true balance between comfort and savings.
Turning off the heating completely at night is a bad idea in most cases.
Lowering the temperature by a few degrees is the best compromise between:

Energy savings,
thermal comfort,
home protection,
and occupant health:
By simply applying this golden rule, you can significantly reduce your bill without shivering under the covers.