Despite their importance for general health, emotion-related factors have rarely been considered in the etiology of late-life insomnia. This study explored the relations between impulsivity, regret experiences, use of different thought-control strategies, and insomnia severity in a sample of older adults whose age ranged from 51 to 98 years. Results revealed that: (a) regret frequency varies across the hours of the day, with a peak in the evening when people are trying to fall asleep; (b) individuals scoring high on impulsive urgency are particularly prone to experience nocturnal regrets; (c) nocturnal regrets are associated with insomnia severity, independently of other well-known risk factors such as depression, sleep-interfering medical conditions, and medications; and (d) the thought-control strategies of self-attacking, thought suppression, and worry are positively associated with the frequency of nocturnal regrets and insomnia severity. These findings indicate that dysfunctional regret regulation plays an important role for sleep disturbances in elderly people.