On January 1, 2023, Sjaak became program manager of MetaHealth and works at the department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), Vrije Universiteit Amsterdam & University of Amsterdam, the Netherlands.

Sjaak studied business at the HTS. He then obtained his master’s degree in Work and Organizational Psychology in Leiden, the Netherlands. Sjaak previously worked in various positions in the field of operational management and human resource management within the Ministry of Defense, the Judiciary, the Royal Netherlands Academy of Arts and Sciences (KNAW), the University of Amsterdam (UvA), the University of Applied Sciences Amsterdam (HvA) and the Vrije Universiteit Amsterdam (VU).