German startup TimeTeller, led by CEO Angela Relógio, has introduced a saliva test kit designed to help individuals understand their personal circadian rhythms. Relógio, a physicist-engineer and molecular biologist, founded the company after years of research in oncology and circadian biology. The startup aims to align medical treatments with patients’ internal biological clocks to reduce side effects and enhance outcomes, especially in cancer therapy, although the direct-to-consumer test currently provides more general insights rather than specific treatment timing.

The company’s primary goal is to advance precision medicine by determining the optimal times to administer cancer treatments, which could improve patient tolerance and efficacy. While the test kit itself is not yet capable of guiding treatment schedules without clinical oversight, it has gained traction among longevity clinics that use the circadian data to customize lifestyle advice related to sleep, nutrition, and physical activity. TimeTeller also envisions applications in managing metabolic and neurodegenerative diseases as well as supporting women's health and athletic performance.

TimeTeller emerged from Berlin’s Charité university hospital and now operates out of Medical School Hamburg, which offers patient access and financial support. The startup secured a significant partnership with Techniker Krankenkasse, one of Germany’s largest health insurers, to reimburse the cost of the test for some cancer patients. This collaboration aims to expand coverage to millions of the insurer’s members, making circadian rhythm testing more accessible for clinical use.

At TechCrunch Disrupt 2026, Relógio highlighted the company’s broader ambition to bring "when" as a fundamental question in precision medicine, emphasizing that timing is crucial to many biological processes. TimeTeller, staffed by a team of about ten people, represents a promising advance in personalized healthcare, leveraging internal biological clocks to better tailor medical interventions and improve patient outcomes.