Sunday is the worst night to get a decent sleep and anxiety about heading back to work on Monday is the likely culprit.
An online survey by research company Toluna asked more than 3000 people in the United States on which night of the week they found it most difficult to fall asleep.
An overwhelming 39 per cent said Sunday, with 70 per cent of those people saying it took them half an hour or longer to get to sleep than on other nights.
The second worst night was Saturday, with 19 per cent rating it the most difficult to get to sleep. The easiest was Thursday, with just 3 per cent rating it the most difficult.
The findings seem to suggest work is to blame, with almost half of all fulltime workers saying Sunday was the most difficult night to sleep on.
People aged 40 to 54 were more likely than others to have difficultly sleeping on Sunday, as were those on higher incomes. Young men took longer to fall asleep on Sundays than other groups, with more men aged 18-39 taking at least half an hour or longer to fall asleep.
Sleep researcher Dr Karyn O'Keeffe, of Massey University's Sleep/Wake Research Centre, said people with busy lives and a lot of responsibilities at work could find it harder to sleep on Sundays than other nights.
"The people who are saying that their sleep is worse on Sunday are the ones who are middle-aged, have the highest incomes, and are at that stage of their life where they're probably likely to have the highest responsibilities," she said. "Potentially there's an argument there that people who have a lot going on in their lives, and have a lot of expectations at work the following day, would find it harder to get to sleep than others."
Dr O'Keeffe said it partly came down to people's sleep behaviour at the weekend.
"If you went out on Saturday night and you've slept in really late on Sunday, trying to get off to sleep at your usual bed time might be a bit harder because you haven't been awake for long enough to get to that sleepy period in the evening."
It was also due to worries about what might happen on Monday.
"It may be things you have to do at work, it might be things you haven't finished yet - it could be anything if Monday is busy for you," Dr O'Keeffe said. "These people are likely to have families as well, so the idea of having to get up and make sure the kids are off to school, that you get to work on time, you don't really want to go to work anyway ... It's a lot of little things all adding up ..."
The results of the online survey of 3101 people, carried out between May 14-16, are available at www.sundaysleep.com
How to get a good night's sleep
* Establish a good routine: Consistent bed times are just as important for adults as they are for children. Try to establish a routine that involves a reminder when it's time to go to bed.
*Have a consistent wake-up time: People focus a lot on the time they go to sleep, but the time you wake up can be just as important.
*Limit activity before bed: Try to do something relaxing before bed. Avoid stimulating activities - don't check your emails and keep the smartphone out of the bedroom.
*Exercise and eat well: Moderate exercise and a healthy diet can help promote a good night's sleep.
*Try to get enough sleep: Most people need between seven and nine hours of sleep a night. People who sleep less can have health problems, impaired learning and memory, and interact poorly with others.