While most of us tumble gratefully into bed most nights, not all of us benefit from a solid night's sleep.
No matter how much you might crave a decent eight hours or how early you go to bed, if your pre-bedtime mood is a negative one, you're likely to suffer from a bad night's sleep.
According to a recent study, trying to sleep while you're in a bad mood ultimately harms your chances of doing so.
With the help of 436 volunteers, psychologists from Iowa State University examined the link between anger levels and sleep habits, and ascertained that the higher the former, the more troubled the latter.
Commenting on their findings, a report into the study states: "Overall, individuals who had poor anger control also had worse objectively and subjectively measured sleep."
"The findings tie actual sleep behaviour to individual differences in anger, suggesting poor anger control plays the most important role, and add to the growing evidence that anger and sleep depend on each other."
If you're suffering from troubled sleep and recognise that you tend to be in a bad mood as the night draws to a close, it's worth trying to resolve any issues before settling down for the night.
Similarly, making note of tasks for the following day, preparing for the morning, and removing digital devices from your bedroom can all work towards lifting your mood, and ensuring a better night's sleep.
The study was published in the Journal of Research in Personality.