Study population: Hodgkin and diffuse large B-cell lymphoma (DLBCL) survivors fulfilling the clinical criteria of CRF and a survivorship of ≥ 3 years will be invited. Fatigue should not be attributable to a clear somatic cause or treatment for secondary cancer in the past year. Moreover, 25 Hodgkin survivors without CRF will be recruited to explore the association between circadian rhythms and CRF.