More than half of people in the UK have experienced poorer sleep since lockdown measures were introduced in March to contain the spread of COVID-19, a study has found.
Worries about money featured prominently in the list of reasons why people were sleeping badly.
Experts said lack of sleep could undermine people's resilience to meet the challenges of the pandemic.
The study by King's College London (KCL) and IPSOS Mori was based on 2254 interviews with UK residents aged 16 to 75, and was carried out online between 20th and 22nd May 2020.
Worries Over Jobs and Money
Among the main findings:
50% of people said their sleep had been more disturbed than usual
The proportion rose to 62% who said they were certain or very likely to face financial difficulties because of disruption caused by the disease
People who found COVID-19 stressful were more than twice as likely as those who did not find it stressful to report disturbed sleep
Prof Bobby Duffy, director of the Policy Institute at KCL, said: "Nearly two-thirds of the UK public report some negative impact on their sleep from the COVID-19 crisis, clearly showing just how unsettling the pandemic and lockdown measures have been for a very large proportion of us. And this is clearly tied to both how stressful we've found the virus itself, and how much we fear the impact of the lockdown on our employment and finances."
Younger people aged 16 to 24 were most likely to report averaging fewer hours sleep a night, with 46% reporting this was the case.
"As with so much about COVID-19, the crisis is affecting people very differently depending on their circumstances, and that includes the most fundamental aspects of life, such as sleep," said Prof Duffy.
Among the survey's other findings:
38% of people reported having had more vivid dreams than usual
The likelihood of having experienced more vivid dreams than normal decreased with age
49% of those who found coronavirus stressful reported having had more vivid dreams than usual, compared with 25% who did not find it stressful
Gideon Skinner, research director at Ipsos MORI, said: "This research is further evidence that the coronavirus crisis is having an impact beyond the immediate physical health and financial effects, and that many people are finding that their wellbeing is suffering even if they haven't been infected, but are just feeling stressed by it all.
"Lack of sleep itself may have further knock-on effects on people's capacity to be resilient in the face of the pandemic, and there are signs that it may be having a disproportionate impact on particular groups: women, younger people, and those facing financial hardship."
Dr Ivana Rosenzweig, head of the Sleep and Brain Plasticity Centre at KCL, commented: "Adequate and good-quality sleep is important to maintain our physical and mental resilience and disturbed sleep is often caused by stress. But we also know that poor sleep can play a role in increasing our levels of stress, which can create a cycle that’s difficult to break. This is reflected by the findings that this effect was greater for those most vulnerable and those who were more concerned about the pandemic."
Dr Rosenzweig also noted that the survey found younger people in particular reporting longer, but less refreshing sleep during the pandemic.
"The associations between depressive symptoms and hypersomnia have been known for some time and again there is a complex two-way relationship between the two, which means they can create a self-perpetuating cycle," she said.
The findings came as a social study into how adults in the UK are feeling about the COVID-19 lockdown found that levels of anxiety and depression had reduced in the past week as restrictions were eased but still remained above usual averages.
The research by University College London, which is ongoing and has not been peer-reviewed, found that depression levels had decreased, particularly amongst those under 60 years of age.
However, depression and anxiety remained highest in young people, those living alone, people with lower household income, those with a diagnosed mental illness, people living with children, and people living in urban areas.
Cheryl Lloyd, education programme head at the Nuffield Foundation, which funded the research, said: "Whilst it is reassuring that levels of anxiety and depression have begun to decrease as lockdown lifts, it is important that researchers continue to carefully monitor the psychological impacts of the pandemic, especially as the social and economic impacts of COVID-19 are likely to be long-lasting."