The term 'LIGHT PERIOD' can be broken down into two crossword solutions: DAY (3 letters) and SUNRISETOSUNSET (15 letters). The term 'LIGHT PERIOD' is used to describe a period of time when there is natural light, usually during the DAY. This period of time is typically associated with the sunrise to sunset hours, which is why the crossword solution SUNRISETOSUNSET (15 letters) is used. The other crossword solution DAY (3 letters) is used to refer to the same period of time, as it is the period of time between sunrise and sunset.