It seems like the answer options are missing from your query. A person who has difficulty sleeping will likely experience many things, but being able to easily fall asleep at night is something they would not experience. Difficulty falling asleep is a key characteristic of insomnia. Other symptoms include daytime fatigue, irritability, difficulty concentrating, mood swings, and decreased productivity. Sleep problems can be caused by a variety of factors, including stress, anxiety, depression, caffeine and alcohol consumption, an irregular sleep schedule, aging, and medical conditions. Sleep disorders like insomnia, sleep apnea, restless leg syndrome, and narcolepsy can also contribute to sleep difficulties.