Heart rate variability and insomnia in depressed patients with breast cancer

Depression is associated with unhealthy autonomic regulation. However, whether patients with breast cancer (BC) with different degrees of depression can be identified from linear and non-linear dynamics in the autonomic nervous system is unclear. We aimed to evaluate the differences in linear and non-linear heart rate variability (HRV) parameters in patients with BC with different degrees of depression and the relationship between HRV parameters and depression and sleep disorders.

A total of 115 patients with BC were enrolled. According to their Self-Rating Depression Scale (SDS) scores, the patients were divided into a non-depressed group, a mildly depressed group and a moderately to severely depressed group. The Pittsburgh Sleep Quality Index (PSQI), HRV, linear index (including time and frequency domains) and non-linear index (including Poincare plot, approximate entropy (ApEn) and short-term fluctuation slope (DFAα1)) were evaluated.

Compared with patients without depssion, patients with mild depression and moderate-to-severe depression had significant differences in the time domain, frequency domain index, the SD perpendicular to the line-of-identity (SD1) and DFAα1 of non-linear HRV and sleep quality. SDS and PSQI scores were correlated with HRV parameters.

The severity of depression in patients with BC is associated with reduced variability, complexity of cardiac dynamics and sleep disturbance.