There are no weight restrictions on the upper pullmans, however there is a weight restriction on the bunk ladder of 130 kg which is approximately 20 Stone.
The upper pullmans are "shock tested" to approximately 300 kg.
Any passenger can sleep in a upper pullman, please bear in mind the bed is elevated therefore a lower berth/cot may be suitable for children/babies.
You will be unable to have a King sized bed configuration in your stateroom if any of the upper pullmans are in use.