"Don't forget it's daylight savings time. You spring forward, then you fall back. It's like Robert Downey Jr. getting out of bed"

In this quote, David Letterman is advising us about daylight cost savings time, a practice where we adjust our clocks to have more daytime in the evenings during the spring and summer season. He utilizes the phrase "spring forward, fall back" to explain how we move our clocks ahead one hour in the spring and then back one hour in the fall. He then compares this to actor Robert Downey Jr. rising, indicating that it can be a little a struggle or change. This quote functions as a funny reminder to not forget about daytime savings time and to adjust our clocks appropriately.