Objectives To explore the associations between stress, sleep disturbances, fatigue severity and social support among primary family caregivers in intensive care units during the early period of ICU hospitalisation.Design Cross-sectional, descriptive correlational study.Setting Intensive Care Units in a teaching hospital in Taiwan.Main outcome measures Perceived stress (Impact of Events Scale-Revised), sleep disturbances (General Sleep Disturbance Scale), fatigue severity (Lee’s Fatigue Scale), social support (Norbeck Social Support Questionnaire) and one op