This interesting HRV study used press tacks that the patients/subjects wore home with a holter monitor to evaluate their HRV over time.  These were body press tacks, not ear.  The points they used over the 72 hour period were LI10, Sp9, Sp6, PC4 with pyonex needles.  The author was kind enough to send a reprint found here.  acupuncture-HRV_NodaYpresstacks hrv depression_2015
Complement Ther Clin Pract. 2015 Aug;21(3):193-200.

Acupuncture-induced changes of vagal function in patients with depression: A preliminary sham-controlled study with press needles.

Author information

  • 1Kanagawa Psychiatric Center, 2-5-1 Serigaya, Kohnan-ku, Yokohama, Kanagawa, 233-0006, Japan; Department of Neuropsychiatry, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan; Centre for Addiction and Mental Health, Department of Psychiatry, University of Toronto, 1001 Queen Street West, Toronto, ON, M6J 1H4, Canada.
  • 2Kanagawa Psychiatric Center, 2-5-1 Serigaya, Kohnan-ku, Yokohama, Kanagawa, 233-0006, Japan.
  • 3Kiiko Matsumoto Acupuncture Clinic, 1223 Walnut Street, Newton Highlands, MA, 02461, USA.
  • 4Kanagawa Psychiatric Center, 2-5-1 Serigaya, Kohnan-ku, Yokohama, Kanagawa, 233-0006, Japan. Electronic address: motoaki@motoaki.com.

Abstract

To study the biological effects of acupuncture on depression, we hypothesized that acupuncture will exert its antidepressant effect through a bottom-up neuromodulation of the autonomic dysfunction in depression. The participants received press needle (PN) acupuncture for 72 h continuously in a sham-controlled design. Psychological assessments and Holter electrocardiography were performed before and after PN acupuncture. We evaluated their autonomic functions through the heart rate variability (HRV). As a result, following PN acupuncture participants showed significant improvement in the Beck’s Depression Inventory scores (P = 0.031), systolic/diastolic blood pressures (P = 0.002/P = 0.011), and coefficient of variation of the R-R interval (P < 0.0001), compared to sham PN. The present findings showed PN acupuncture induced alterations in vagal function, blood pressure, and Beck’s Depression Inventory scores. It was suggested that vagal stabilization effect by acupuncture may be associated with the therapeutic mechanism in depression.