Objectives: To determine whether the occurrence of cardiac symptoms is related to sleep disturbances.
Design: An epidemiological survey by means of a questionnaire.
Setting: The county of Jämtland in northern Sweden.
Subjects: Randomly selected women (6000) aged 40-64 years, with a similar number of women in each 5-year age group. A total of 3669 responded.
Main outcome measures: Sleep disturbances and cardiac symptoms.
Results: In total, 81.9% of the women reported a good night's sleep. Amongst them, 0.4% stated that they were troubled by both spasmodic chest pain and a sensation of irregular heart beat, 0.8% spasmodic chest pain alone, 5.8% irregular heart beat and 93.0% neither of these conditions. The corresponding frequencies amongst the women who slept poorly were 1.5, 1.8, 15.0 and 81.7%, respectively (P < 0.0001). Amongst the subjects with reported sleep complaints, there was an increase in heart symptoms, both in those with trouble falling asleep, frequent awakenings and difficulty in getting to sleep again, and in those who awoke too early in the morning. Spasmodic chest pain was 8.8 (1.9-40.3) times and irregular heart beat 7.7 (3.3-18.1) times more common in women with nightmares almost every night than in those who never experienced nightmares. Daytime sleepiness was also associated with increased heart symptoms.
Conclusion: Poor sleep was associated with an increase in spasmodic chest pain and irregular heart beat.