“Turn in for the night” is an idiomatic expression that means to go to bed or to retire for the evening. When someone says they are going to “turn in,” it typically implies that they are ready to sleep or rest after a day’s activities. The phrase can suggest a sense of winding down or concluding the day’s events, often used when someone feels tired or ready to end their day. For example, if someone has had a long day at work, they might say, “I’m going to turn in for the night,” indicating that they plan to go to sleep soon.