Cracks or sags in a plaster ceiling can seem like small problems and not worth bothering to repair. In fact, there are some very good reasons why they should be fixed as soon as possible.
Firstly, small problems are not likely to stay small for long. A crack in the ceiling may be so thin that you cannot see it unless you are looking for it. Unfortunately, something caused that crack and it is not likely to go away. Problems with ceilings are often caused by water leaking through the roof and collecting on the ceiling. This is only going to get worse if it is not addressed and means that the ceiling damage will worsen. The sooner a problem is fixed, the easier and cheaper it will be, so don't leave things to get worse.
The second reason was alluded to above. Whatever caused your ceiling damage will need to be fixed in order for your ceiling to stay in good repair. If there is a leak in your roof, you could find discoloured cracks or holes in your ceiling. You will not be able to cure this without fixing the leak. There may also be structural problems that are causing the plaster to crack. These must be investigated as soon as possible, in case there are serious problems that need to be addressed.
A third reason is that problems with your ceiling just look unpleasant. Your home should be a place where you can relax and be comfortable. Even cosmetic problems that spoil the appearance of your home can make it seem less pleasant. By keeping your house in good repair you can have a home that will make you feel proud.
Finally, it may be worth thinking about the value of your house. You may not be intending to sell your home in the near future, but things can always change and the time may come when you will want the best possible price for your house. The best way to do this is to keep it in good repair. Those jobs you have been putting off will probably not get done in the run-up to a house sale, so get the ceiling repaired now and preserve its value.
A problem with a plaster ceiling could point towards a more serious problem that needs to be fixed. Call in a plaster ceiling repair service as soon as you see anything wrong, and you will not have to worry about those problems getting worse.