Process for the production of viscoelastic flexible polyurethane foams which are obtainable by reacting component A: A1 40 to 90 parts by weight of at least one polyether polyol with a functionality of 2 to 6, an oxyethylene content of > 60 wt.%, more than 50 mol% of primary OH groups and a hydroxyl number (OH number) of ≥ 10 mg KOH/g to ≤ 112 mg KOH/g; A2 0 to 40 parts by weight of at least one polyether polyol with a functionality of 2 to 6, an oxyethylene content of 0 to 30 wt.%, less than 50 mol% of primary OH groups and an OH number of ≥ 8 mg KOH/g to ≤ 112 mg KOH/g, A3 0 to 40 parts by weight of at least one polyether polyol with a functionality of 2 to 6, an oxyethylene content of 0 to 50 wt.%, more than 50 mol% of primary OH groups and an OH number ≥ 8 mg KOH/g to ≤ 112 mg KOH/g A4 0 to 30 parts by weight of at least one polyether polyol with a functionality of 2 to 6, an oxyethylene content of 0 to 30 wt.%, less than 50 mol% of primary OH groups and an OH number ≥ 112 mg KOH/g the parts by weight of components A1 to A4 adding up to 100; A5 0.5 to 25 parts by weight (based on the sum of the parts by weight of components A1 to A4) of water and/or physical blowing agents; A6 0.5 to 5.0 parts by weight (based on the sum of the parts by weight of components A1 to A4) of urea; A7 0.05 to 30 parts by weight (based on the sum of the parts by weight of components A1 to A4) of auxiliary substances and additives such as a) catalysts, b) surface-active additives, c) pigments or flame retardants; A8 0 to 10 parts by weight (based on the sum of the parts by weight of components A1 to A4) of compounds selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, sorbitol, glycerol, ethylene glycol and propylene glycol, with component B comprising diisocyanates, polyisocyanates, mixtures of diisocyanates and/or polyisocyanates, mixture of isomers or prepolymers,, the production taking place at an index of 50 to 150, and all the parts by weight of components A1 to A8 being standardized so that the sum of the parts by weight of A1 +A2+A3+A4 in the composition is 100. A1 40 to 90 parts by weight of at least one polyether polyol with a functionality of 2 to 6, an oxyethylene content of > 60 wt.%, more than 50 mol% of primary OH groups and a hydroxyl number (OH number) of ≥ 10 mg KOH/g to ≤ 112 mg KOH/g; A2 0 to 40 parts by weight of at least one polyether polyol with a functionality of 2 to 6, an oxyethylene content of 0 to 30 wt.%, less than 50 mol% of primary OH groups and an OH number of ≥ 8 mg KOH/g to ≤ 112 mg KOH/g, A3 0 to 40 parts by weight of at least one polyether polyol with a functionality of 2 to 6, an oxyethylene content of 0 to 50 wt.%, more than 50 mol% of primary OH groups and an OH number ≥ 8 mg KOH/g to ≤ 112 mg KOH/g A4 0 to 30 parts by weight of at least one polyether polyol with a functionality of 2 to 6, an oxyethylene content of 0 to 30 wt.%, less than 50 mol% of primary OH groups and an OH number ≥ 112 mg KOH/g the parts by weight of components A1 to A4 adding up to 100; A5 0.5 to 25 parts by weight (based on the sum of the parts by weight of components A1 to A4) of water and/or physical blowing agents; A6 0.5 to 5.0 parts by weight (based on the sum of the parts by weight of components A1 to A4) of urea; A7 0.05 to 30 parts by weight (based on the sum of the parts by weight of components A1 to A4) of auxiliary substances and additives such as a) catalysts, b) surface-active additives, c) pigments or flame retardants; a) catalysts, b) surface-active additives, c) pigments or flame retardants; A8 0 to 10 parts by weight (based on the sum of the parts by weight of components A1 to A4) of compounds selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, sorbitol, glycerol, ethylene glycol and propylene glycol,