Social media usage has increased over recent years and has been associated with negative effects on health and wellbeing. This study explored whether reducing smartphone screentime would improve health and wellbeing. Fifty students completed a battery of questionnaires regarding their health, immune function, loneliness, sleep, anxiety, and depression. They were allocated randomly to groups either using smartphones as normal (No Change), reducing usage by 15 min per day (Reduce), or reducing use by 15 min and substituting another activity during this time (Reduce + Activity). After 3 months, they completed the same questionnaires again. There was unexpectedly low compliance with the Reduce + Activity (leisure substitution) intervention. In contrast, there was a significant reduction in screentime for the Reduce group compared to the other two groups. There was a significant improvement in the Reduce group in general health, immune function, loneliness, and depression compared to the other groups. These findings extend previous results from similar studies and suggest limiting screentime may be beneficial to health and wellbeing.