Thanks so much for answering!
It is central heat and air-conditioning in this house. The landlord has no desire to add more insulation, and you're right...it needs more.
The furnace does have to compensate in the morning--first thing I do when I get up is turn the thermostat back up to 71 or so. I've wondered with all that extended run time in the morning if I was just losing whatever savings I had gained during the night.
I think I'll take your advice and try leaving it at 68 during the night.
From your comments....were you saying that it is better for heat pumps to run longer, but not central heat units?
The man who installed the digital thermostat set it to have a longer run or cycle time (or whatever the term should be) instead of the short one--he specifically said that. Guess he knew what he was doing. The furnace seems to run an awfully long time when it's on, no matter what the thermostat is set on-- the lower or higher degrees alike.
I really appreciate your comments and hope you don't mind answering another question for me. :)
The reason you don't want the central air {in the air conditioning mode} or a heat pump in either mode to cycle off and on a lot is due to wear and tear on the compressor motor which is a sealed unit.
I've been out of it for a while but on a house my off the top of my head guess is about $800-$1000 for a 2-3 ton compressor to be replaced. I could be off a few hundred either way but I think that is a low bid. Most problems in electrical motors happen on start up as that is when it is using the highest amperage and under the most stress on the windings.
I saw your next post saying it is gas heat. Cycling off and on too often won't hurt anything in general but the fan motor and relays in that case. It's not yours to worry about though :>}
My guess is you're in a colder climate and your furnace unfortunately for you since you pay the gas bill is trying to heat the great outdoors as well. Here's you a few simple things that don't cost nothing. Daytime winter curtains open. Nights curtains closed as they do have some insulating value. Throw rugs or a towel in front of outside doors to block the air. Keep the filters changed once a month. That is to your benefit. If the air flow is blocked you don't get the right circulation. Sorry I can't help more but if the house is lacking attic insulation {which can be corrected the easiest} it's gonna keep running as heat tends to rise and goes out the ceiling. One good way to kind of tell how good your insulation is serving you is to see how much snow gathers on the roof in say a 3-4 inch snow. If none is laying or it melts off the roof fast within the day you likely have poor insulation.