The hygrostat of OptiClimate, has a light sensor and a humidity sensor that regulate dehumidification during night mode.
The hygrostat light cell activates the OptiClimate night mode and with this, the dehumidification of the room. The humidity sensor regulates the desired humidity during night mode.
When the lights come back on, the hygrostat activates the day mode of the OptiClimate.
The hygrostat is included with the purchase of an OptiClimate, but can also be purchased separately.