How can light therapy be effective?

Light therapy can be effective in treating problems associated with sleep patterns, stress, moods, jaundice in newborns, and seasonal affective disorders. While light therapy is not typically used for overcoming weight problems or helping with allergies, it is specifically known for its benefits in regulating sleep patterns. Therefore, the correct answer is 'working with sleep patterns.' Choices A, B, and C are incorrect as light therapy is not commonly utilized for overcoming weight problems, helping with allergies, or as a general alternative medical treatment.