A magnetoencephalography measurement device, comprising: an assembly of a plurality of sensors placed inside a Dewar vessel; the Dewar vessel, when in use, storing liquid helium to cool the assembly of sensors to a superconductive temperature, the Dewar vessel comprising a body portion, a mouth, and a helmet portion formed in the body portion for receiving a patient's head, the assembly of sensors being arranged around the helmet portion inside the Dewar vessel; a cryocooler apparatus (132,134,136) suspended inside the Dewar vessel; a lid (120,124) sealing the mouth, the lid (120,124) comprising a first orifice allowing a flow of helium gas from a storage tank to the Dewar vessel and allowing pumping of boiled helium gas to the storage tank from the Dewar vessel, when the Dewar vessel stores liquid helium and the storage tank stores helium gas; the storage tank in gaseous communication with the Dewar vessel via a line (101,103,104) connected to the first orifice, when the Dewar vessel stores liquid helium and the storage tank stores helium gas, the line comprising a pressure controlling device; a compressor for pumping helium gas from the Dewar vessel to the storage tank, when the Dewar vessel stores liquid helium and the storage tank stores helium gas; characterized in that a control unit comprising at least one processor and a memory storing instructions that, when executed, cause the control unit to switch the cryocooler apparatus (132,134,136) on or off based on a comparison of a current time to at least one scheduled inactivity or at least one scheduled activity period, respectively, for the magnetoencephalography measurement device stored in the memory, the inactivity period allowing re-liquefaction of the helium gas flowing from the storage tank to the Dewar vessel by the cryocooler apparatus (132,134,136), when the Dewar vessel stores liquid helium and the storage tank stores helium gas; and wherein a sum of durations of the at least one scheduled activity period within a time period comprising the at least one scheduled activity period do not exceed a predefined threshold value, the threshold value being selected to maintain at least a minimum level of liquid helium in the Dewar vessel. an assembly of a plurality of sensors placed inside a Dewar vessel; the Dewar vessel, when in use, storing liquid helium to cool the assembly of sensors to a superconductive temperature, the Dewar vessel comprising a body portion, a mouth, and a helmet portion formed in the body portion for receiving a patient's head, the assembly of sensors being arranged around the helmet portion inside the Dewar vessel; a cryocooler apparatus (132,134,136) suspended inside the Dewar vessel; a lid (120,124) sealing the mouth, the lid (120,124) comprising a first orifice allowing a flow of helium gas from a storage tank to the Dewar vessel and allowing pumping of boiled helium gas to the storage tank from the Dewar vessel, when the Dewar vessel stores liquid helium and the storage tank stores helium gas; the storage tank in gaseous communication with the Dewar vessel via a line (101,103,104) connected to the first orifice, when the Dewar vessel stores liquid helium and the storage tank stores helium gas, the line comprising a pressure controlling device; a compressor for pumping helium gas from the Dewar vessel to the storage tank, when the Dewar vessel stores liquid helium and the storage tank stores helium gas; characterized in that a control unit comprising at least one processor and a memory storing instructions that, when executed, cause the control unit to switch the cryocooler apparatus (132,134,136) on or off based on a comparison of a current time to at least one scheduled inactivity or at least one scheduled activity period, respectively, for the magnetoencephalography measurement device stored in the memory, the inactivity period allowing re-liquefaction of the helium gas flowing from the storage tank to the Dewar vessel by the cryocooler apparatus (132,134,136), when the Dewar vessel stores liquid helium and the storage tank stores helium gas; and wherein a sum of durations of the at least one scheduled activity period within a time period comprising the at least one scheduled activity period do not exceed a predefined threshold value, the threshold value being selected to maintain at least a minimum level of liquid helium in the Dewar vessel.