Pillows are often ignored, and not part of the "must change" priority list.
However, the pillows need to be changed after every 3 to 4 years.
If you regularly use the Sleepwell pillows, then it is better to change them with new Sleepwell pillows after every four years.
You can also check the signs of pillow damage, including sagging, changed shape, and comfort level to change it.