Light loggers are specifically designed to monitor indoor light changes. Using light sensors, light loggers monitors and records when an indoor light source is turned on, how long the light was on, and the time it was turned off. Most light loggers also have the added feature of determining room occupancy, and how often the room us used. This data is stored within the instrument and then retrieved using its software installed in a computer.

Software in some models also facilitate data analysis given that most models are integrated with a feature that exports their data to a spreadsheet when uploaded to a computer. Most models are bundled with data analysis software for additional analyzing tools and features.

Light loggers are mainly used for energy consumption and to determine room occupancy patterns. Rooms are compared based on how long their light sources where turned depending on whether there was someone in the room. These measurements are needed to comply with existing state regulations about electrical consumption, and can be used to identify areas or rooms where possible savings can be made.