 Proposed Intervention. HRV-B training will follow a previously established, standardized protocol. The primary HRV coherence, pain, stress and exploratory outcomes insomnia, fatigue, depression, cognition. Outcomes will be assessed at 4 time points: pre-training; post-training, one week after the 6 weekly treatments are over; at 4 weeks follow-up after post-training, and at an 8-week post-training follow-up total time of participation is 16 weeks from pre-training to 8 week follow-up. There will be no HRV-B training at the 8 week follow-up, only assessment. Standardized procedures will characterize HRV coherence and other frequency- or time-domain HRV measures, and validated instruments will be used to assess pain and stress. Wrist actigraphy will characterize insomnia via continuous, 24-hourday personal monitoring of restactivity rhythms at 1-week intervals coinciding with the baseline pre-training baseline, post-training, and 8-week follow-up assessments. The investigators will provide portable data-logging devices for practicing HRV-B at home. Sham intervention subjects will have pulse and respiration monitored but not receive active training; instead they will view a static, relaxing nature picture on a computer screen. 