We understand that the union Unison has lodged an appeal against the Court of Appeal's decision last month in Mencap v Tomlinson-Blake which decided that workers who are expected to sleep during their shifts are only "available for work" and are only entitled to receive the NMW if they are woken up to perform work.
Unison say that it believes the "Court of Appeal got this decision wrong and they will do everything they can to reverse it".
Technically, Unison are seeking leave to appeal to the Supreme Court. Once it clears that hurdle, a date will be set down to determine the issue.
This announcement will create further uncertainty for businesses who rely on sleep in shift workers to provide cover.
Background to case:
Mencap were contracted to provide support and care to vulnerable adults. Ms Tomlinson-Blake and others carers provided 24 hour support to two men in their home. She worked either a day shift or a sleep in shift.
Sleep in shifts lasted nine hours and she received a flat rate of £29.05 for this. Ms Tomlinson-Blake had her own room and could sleep during the shift, but was required to keep “a listening ear out” during the night and provide support where needed and to respond to any emergencies. The need was “real but infrequent” and Ms Tomlinson-Blake had only had to intervene on six occasions during the previous 16 months.
She argued that she should receive the NMW for every hour of her sleep in shift.