A controlled residential ventilation system is above all also a gain in comfort. With a geothermal heat exchanger, you can also moderately cool in summer (however, it does not work miracles).
I once slept directly on the floor on a radiant floor heating system for a while. That was great (I had the heating completely off during the day). And if you have the comfort of a bed, I don't see the problem anyway. Furthermore, the heating output and thus the floor temperature depend on the insulation. A well-insulated house with controlled residential ventilation and heat recovery requires less heating output. You hardly notice when the heating is completely off for a few hours. You can easily turn the heating down a bit at night if the warm floor under the bed is a problem.
And with underfloor heating, the response time depends on the overall structure. I don't think it makes sense to combine underfloor heating (low flow temperature) with wall radiators (high flow temperature). The possibility to lower the temperature at night also depends on the construction type. A well-insulated solid structure cools down slowly.
: The keyword is entropy. Strictly speaking, it initially takes more energy if you let an unused room cool down. And with an electric heater, that would also be the cheaper option. Only when flow temperature, temperature gradients, and optimal system performance come into play does it become cheaper to keep a room constantly at a moderate temperature rather than heating it up on demand.