Below are data from: 1) A **questionnaire** concerning demographic information, changes in health behaviours as a result of lockdown, and pandemic-/lockdown-related experiences (Sample file) 2) **Negative mood scale** (Mood file) 3) **Five cognitive tasks** (Iowa gambling, flanker Acc & RT, symbol learning, time production, and DSST Acc & RT files) The **Variables file** provides more information about questions and coding schemes for categorical variables. The **Performance notes file** lists participants with suboptimal performance on the DSST and flanker tasks. The **Materials folder** provides stimuli/materials used in the study. For more information on the **data from the change in health behaviours questions and mood scale**, see "Changes in diet, sleep, and physical activity are associated with differences in negative mood during COVID-19 lockdown" by Ingram, Maciejewski, & Hand (2020) For more information on the **data from the cognitive tasks**, see "Social isolation during COVID‐19 lockdown impairs cognitive function" by Ingram, Hand, & Maciejewski (2021)