Coronavirus disease 2019 (COVID-19) is a global pandemic. Measures to reduce transmission of the virus have altered usual activities, routines, and livelihoods, and have had a significant impact on mental health. The current study aims to examine the potential alterations in psychological wellbeing, mental health, sleep and diurnal preference due to the COVID-19 pandemic. A cross sectional online questionnaire-based study with n = 200 participants (aged 18–62; 7.86.0% female, 93.0% white, 92.5% UK-based, 73.5% students). Data were collected between 15 th April and 8 June 2020. Participants answered questions on lifestyle changes and their concerns and worries about COVID-19, and completed the SCI, PHQ9, GAD7, PWB18, UCLA3 and MEQ. Results showed self-isolation was linked to lower psychological well-being, and increased loneliness, anxiety and depression. Home-working was related to a shift in diurnal preference. Reduced work/income was related to decreased psychological well-being and sleep quality and increased anxiety, depression, loneliness and. Intensity of worried thoughts and concerns about COVID-19 were positively correlated with anxiety, depression and negatively with sleep quality. In conclusion, the social, occupational and economic disruption due to COVID19 has had a negative impact on psychological well-being. However, the transition to home-working may have been somewhat beneficial for some individuals in terms of sleep. These findings should be taken into account by policy makers during the transition to the ‘new normal’ post-pandemic.