A suspension device for supporting a mattress comprising: a base part comprising slots for attachment to a bedding structure; a top part comprising slots for receiving slats therein; a spring element provided between the base and the top part for resiliently suspending the slats in view of the bedding structure, whereby the spring element comprises at least: • a first spring element extending between the base part and the top part of the device; and • a second spring element extending between the base part and the top part of the device; and • an adjustable member allowing adapting the spring characteristic of the suspension device, characterised in that said second spring element comprises a first spring portion fixed to the base part and extending towards the top part; a second spring portion fixed to the top part and extending towards the base part; and a bridge portion connecting the free ends of the first and second spring portions (6a & 6b), whereby the first and second spring portions are spaced apart in a direction perpendicular to the suspension direction and the bridge portion defining an abutment surface and in that the adjustable member is movable in a guide or series of slots provided in the top part and comprises an actuating member that is in contact with the abutment surface, such that repositioning the adjustable member in said guide or series of slots changes the contact position of the actuating member along the abutment surface, thereby varying the spring characteristic of the device. a base part comprising slots for attachment to a bedding structure; a top part comprising slots for receiving slats therein; a spring element provided between the base and the top part for resiliently suspending the slats in view of the bedding structure, whereby the spring element comprises at least: • a first spring element extending between the base part and the top part of the device; and • a second spring element extending between the base part and the top part of the device; and • an adjustable member allowing adapting the spring characteristic of the suspension device, • a first spring element extending between the base part and the top part of the device; and • a second spring element extending between the base part and the top part of the device; and • an adjustable member allowing adapting the spring characteristic of the suspension device, characterised in that said second spring element comprises a first spring portion fixed to the base part and extending towards the top part; a second spring portion fixed to the top part and extending towards the base part; and a bridge portion connecting the free ends of the first and second spring portions (6a & 6b), whereby the first and second spring portions are spaced apart in a direction perpendicular to the suspension direction and the bridge portion defining an abutment surface and in that the adjustable member is movable in a guide or series of slots provided in the top part and comprises an actuating member that is in contact with the abutment surface, such that repositioning the adjustable member in said guide or series of slots changes the contact position of the actuating member along the abutment surface, thereby varying the spring characteristic of the device.