In this article, Heather Fern discusses her twin babies' nighttime routine when they were 6 months old. She emphasizes the importance of establishing a consistent bedtime routine to help them sleep better. Fern shares the activities they do before bed, such as a warm bath, massage, and reading a book. She also mentions using calming techniques like soft music and dim lighting. Overall, the main idea is to create a soothing and predictable environment to promote a good night's sleep for the babies.