Luminescent cycle regulator and fertility indicator

A natural family planning device (10) and method which improves the regularity of the female cycle and indicates days during the cycle when there is an increased probability of conception during intercourse. The device (10) provides automated light therapy regimens of varying intensity and duration while the user sleeps with the aim of synchronizing the user's cycle to the illumination cycle provided by the device thereby improving the regularity of the user's cycle. The device also indicates (50, 55) to the user which days of the synchronized cycle represent the highest likelihood of conception during intercourse. This enables the user to time intercourse to coincide with or avoid the dates of increased probability of conception depending on the desire of the user to become or avoid becoming pregnant.