It is a fundamental truth that not all mattresses are created equal. In fact, the exact opposite is true, there is a wide array of different quality mattresses out there, from the downright unhealthy through to the incredibly comfortable and supportive high end mattresses that can actually improve your health.
Spring mattresses have been around for the last couple of centuries and have really outlived their used by date. All it takes is one spring out of place and you will know about it. Spring mattresses also have large internal cavity where dust mites and bed bugs can thrive, meaning you can get sick or itchy just from lying on them
Standard foam mattresses are a cheap option, and you definitely get what you pay for with these. They deteriorate even quicker than a spring mattress and before long you will be stuck in a rut, unable to roll out. They also harbour bed bugs and dust mites, making them unhealthy and unhygienic.
Memory foam mattresses are far superior, they are the most supportive yet supple and comfortable. Also, they will last for many more years than the other two styles of mattress and because of their construction, they are far less likely to offer refuge to bed bugs and dust mites.