There are lots of different studies to prove the success of sea sickness bracelets. Initially, a 2005 study concluded that P6 acupressure bracelets increased tolerance of nausea in females with a history of motion sickness. You can find more about this study in the following journal;
P6 Acupressure Increases Tolerance to Nauseogenic Motion Stimulation in Women at High Risk for Postoperative Nausea and Vomiting Aidah Alkaissi, RN/PhD, Torbjörn Ledin, MD/PhD, Lars M. Odkvist, MD/PhD, and Sigga Kalman, MD/PhD Canadian Journal of Anesthesia 2005, 52: 7; pp 703-709.
Other literature includes:
Rose Ferrara-Love, MSN, RN, CPAN, CAPA, Nonpharmacologic Treatment of Postoperative Nausea, 1996 American Society of PeriAnesthesia Nurses.
Stannard, DM (1989) Pressure Prevents Nausea, Nursing Times p33-34.
Effect of Stimulation of the P6 Anti-emetic Point on Postoperative Nausea and Vomiting. British Journal of Anesthesia, 1980.