Method for producing molded flexible polyurethane foams having horizontally arranged zones of differing hardness, characterized in that in step 1) a flowable reaction mixture I is imported into the mold cavity and free-foamed, 2) from 1 to 6 min after importing said reaction mixture I into the mold cavity at least one flowable reaction mixture II is imported into the mold cavity, 3) curing in the mold, and 4) demolding the molded flexible PU foam formed after step 4, wherein said flowable reaction mixture I forms a flexible PU foam having an apparent density of 30 to 90 kg/m 3 and said flowable reaction mixture II forms a molded flexible PU foam having an apparent density of 30 to 85 kg/m 3, wherein step 1 utilizes a reaction mixture I containing the following components: component I-A1 I-A1.1 at least one polyether polyol having a functionality of 2 to 8, a DIN 53240 hydroxyl number in the range from 20 to 70 mg KOH/g and a polyoxypropylene content in the range from 50 to 100 wt% and a polyoxyethylene content in the range from 0 to 50 wt%, I-A1.2 optionally at least one polyether polyol having a hydroxyl functionality of 2 to 8, a DIN 53240 OH number in the range from 50 to 65 mg KOH/g and a PO content in the range from 45 to 55 wt% and an EO content in the range from 45 to 55 wt%; I-A1.3. optionally at least one dispersion of a polymer in a polyether polyol, wherein the dispersion has a DIN 53240 OH number in the range from 10 to 30 mg KOH/g and wherein the polyether polyol has a hydroxyl functionality of 2 to 6, a PO content in the range from 70 to 90 wt% and an EO content in the range from 10 to 30 wt%; I-A1.4 optionally at least one polyether polyol having a functionality of 2 to 8, an OH number in the range from 220 to 290 mg KOH/g and a PO content of up to 25 wt% and an EO content of at least 75 wt%; A2 water and/or a physical blowing agent, A3 optionally isocyanate-reactive hydrogen compounds having an OH number of 140 mg KOH/g to 900 mg KOH/g, A4 auxiliary and added-substance materials such as a) catalysts, b) surface-active added-substance materials, and c) pigments or flame retardants, and B di- and/or polyisocyanates, wherein the foam is produced at an isocyanate index of 70 to 130. 1) a flowable reaction mixture I is imported into the mold cavity and free-foamed, 2) from 1 to 6 min after importing said reaction mixture I into the mold cavity at least one flowable reaction mixture II is imported into the mold cavity, 3) curing in the mold, and 4) demolding the molded flexible PU foam formed after step 4, component I-A1 I-A1.1 at least one polyether polyol having a functionality of 2 to 8, a DIN 53240 hydroxyl number in the range from 20 to 70 mg KOH/g and a polyoxypropylene content in the range from 50 to 100 wt% and a polyoxyethylene content in the range from 0 to 50 wt%, I-A1.2 optionally at least one polyether polyol having a hydroxyl functionality of 2 to 8, a DIN 53240 OH number in the range from 50 to 65 mg KOH/g and a PO content in the range from 45 to 55 wt% and an EO content in the range from 45 to 55 wt%; I-A1.3. optionally at least one dispersion of a polymer in a polyether polyol, wherein the dispersion has a DIN 53240 OH number in the range from 10 to 30 mg KOH/g and wherein the polyether polyol has a hydroxyl functionality of 2 to 6, a PO content in the range from 70 to 90 wt% and an EO content in the range from 10 to 30 wt%; I-A1.4 optionally at least one polyether polyol having a functionality of 2 to 8, an OH number in the range from 220 to 290 mg KOH/g and a PO content of up to 25 wt% and an EO content of at least 75 wt%; I-A1.1 at least one polyether polyol having a functionality of 2 to 8, a DIN 53240 hydroxyl number in the range from 20 to 70 mg KOH/g and a polyoxypropylene content in the range from 50 to 100 wt% and a polyoxyethylene content in the range from 0 to 50 wt%, I-A1.2 optionally at least one polyether polyol having a hydroxyl functionality of 2 to 8, a DIN 53240 OH number in the range from 50 to 65 mg KOH/g and a PO content in the range from 45 to 55 wt% and an EO content in the range from 45 to 55 wt%; I-A1.3. optionally at least one dispersion of a polymer in a polyether polyol, wherein the dispersion has a DIN 53240 OH number in the range from 10 to 30 mg KOH/g and wherein the polyether polyol has a hydroxyl functionality of 2 to 6, a PO content in the range from 70 to 90 wt% and an EO content in the range from 10 to 30 wt%; I-A1.4 optionally at least one polyether polyol having a functionality of 2 to 8, an OH number in the range from 220 to 290 mg KOH/g and a PO content of up to 25 wt% and an EO content of at least 75 wt%; A2 water and/or a physical blowing agent, A3 optionally isocyanate-reactive hydrogen compounds having an OH number of 140 mg KOH/g to 900 mg KOH/g, A4 auxiliary and added-substance materials such as a) catalysts, b) surface-active added-substance materials, and c) pigments or flame retardants, and a) catalysts, b) surface-active added-substance materials, and c) pigments or flame retardants, and B di- and/or polyisocyanates, wherein the foam is produced at an isocyanate index of 70 to 130.