Mobile phone Intervention for Drinking in Young people (MIDY)

The intervention will be delivered by SMS on drinking occasions on Friday and Saturday nights over a 6-week period. The intervention will consist of hourly Ecological Momentary Assessments (repeated, real-time behavioural surveys) and tailored feedback. Participants will be sent an SMS at 6pm every Friday and Saturday night during the trial period, with a link to an online survey. This will ask about their plans for the evening and, if they are going out, details about what they plan to do. If they plan to go out, participants will then receive hourly SMS reminders (7pm to 3am) to complete a very brief online questionnaire. The questionnaire will involve hourly reports of their alcohol consumption and spending, where they are, and their mood. They will then receive an individually tailored feedback message via SMS in response to these data, which aims to stop or slow down their drinking, or avoid harmful consequences of drinking. The next day they will be sent a follow-up message with a link to another short survey to confirm details of the night, including total drinks consumed. Every Monday, they will receive an SMS-linked survey asking them to report on the highest number of alcoholic drinks consumed in a single occasion in the past week (peak number of drinks), and the night of the week it was consumed.