Final answer:
The correct nursing diagnosis for a patient exhibiting irritability, daytime sleepiness, chronic difficulty in falling asleep, and fatigue is Insomnia.
Step-by-step explanation:
The patient's symptoms of irritability, being sleepy during the day, difficulty in falling asleep, and chronic tiredness are indicative of sleep-related issues. The most appropriate nursing diagnosis for the patient, who is experiencing symptoms including irritability, daytime sleepiness, chronic difficulty falling asleep, and fatigue, is Insomnia. This condition is characterized by consistent difficulty in falling or staying asleep, and other criteria include experiencing these symptoms for at least three nights a week for at least one month's duration.