Well, there is no general answer to this question as it depends on the type of plan that you have. While it may be safe to sleep with your portable Heating & Air Conditioning units, it could be dangerous to have the same temperature settings as while I was in the day & sleep in those same temps. Most homeowners, I included, use smaller systems such as the oil oil furnace & the space oil furnace for emergency heating or when the central heating fails. These smaller electric furnaces are equipped with a safety feature that enables the component to switch off in case of overheating. Therefore it is safe to sleep with these units on as long as you lower the sizzling settings. Other major units such as the geo heat pump & the ductless Heating & Air Conditioning can cause the energy bills to shoot up when left on, overnight, & on temperatures set too high. Even if there are unusual energy saving help tips that one can employ. One of the factors that can influence the option to leave the heating & air conditioning on the same day settings is the lack of a controller that allows you to adjust the temperatures on your bed. A straight-forward solution for this would be a wireless control unit. At times when our component is fresh from a gas furnace/heater tune-up session, I like living it on since the maintenance is usually improved after the sessions. The decision to leave your component on will honestly be influenced by when boiler replacement was done. Heating & Air Conditioning techs proposedthat it would be more lavish to leave a component that was installed a long time ago. I also earned the same recommendation when I visited the heating corp to purchase a new heating component last fall.