The aim of this study was to assess the impact of variations in the 3-hourly geomagnetic activity level during the period of the lowest solar and geomagnetic activity on the psychological state of patients who underwent coronary artery bypass grafting or valve surgery. The study was performed in Kaunas, Lithuania, during 2008–2012. The psychological state of 233 patients was assessed using the Symptom Checklist-90-Revised instrument (SCL-90-R) at 1.5 months, 1 year, and 2 years after the surgery (N = 531). During days of a negative difference between k-index sums at 18:00–00:00 h and 06:00–12:00, all SCL scores were statistically significantly higher. A low k- sum during 18:00–00:00 on the previous day was associated with an increase in anxiety, anger–hostility, phobic anxiety, paranoid ideation, and psychoticism. The combination of these conditions was associated with higher values of the SCL scores. These effects were observed at 1.5 and 12 months after the surgery. During the period lasting from 18:00 on the previous day to 12:00 on the day of the test, variations in k-indices that were not in line with the general trend of changes in the k-index were associated with a poorer psychological state in patients after open-heart surgery.
Venclovienė et al. (Sun,) studied this question.