If you want a night drop, and a bullet-proof, no-fail setup, take four thermostats set two to the day time temperature and hook these in series to a timer (set for the day time hours), and take the other two, set them for the night temp., and hook them in series straight to house power. As the daytime ones go off, the temperature will fall till the night time ones kick in, in the day the temp. will be above the night thermostats' setting and they will not activate.
Or you could just go out and buy a single programmable, timed thermostat, since the higher end devices are much less likely to "stick" and roast your whatever it is (you haven't told us what you want to heat, now spill the beans please).
-----
Currently
2.0 F. silvestris (NFO)
1.1 F. pardalis (Ambilobe)
0.0.3 D. tinctorius (Suriname Cobalt)
0.0.3 D. tinctorius (Weygoldt)
0.0.~100 E. prosticus