If you ever feel frustrated by people who seem to be able to exist on just a few hours kip, you might be glad to hear that new studies suggest it may be better to stay in bed.
People who rise with the lark are more likely to lie and cheat in the evening, American researchers have found.
And people who identify as night owls are more likely to behave "unethically" in the morning.
So it might be an all-round good idea to enjoy your full eight hours, because when a person's energy levels are depleted dishonourable temptations become harder and harder to resist.
A summary of the findings, published in the Harvard Business Review, stated: "In contrast to the assumption that good people typically do good things, and bad people do bad things, there is mounting evidence that good people can be unethical and bad people can be ethical, depending on the pressures of the moment."
Building on previous research that indicated people become more unethical as the day wears on, the researchers examined the relationship between energy patterns and ethics.
They focused on the circadian rhythm, which controls wakefulness and sleep and varies across individuals, meaning that some people naturally rise earlier in the day, while others tend to be night "owls" that stay up late.
The researchers predicted that these different sleep rhythms would be reflected in different patterns of ethical and unethical behaviour throughout the day.
In the first study they tested behaviour in the morning by asking participants to complete a simple matrix task in which they were paid additional money for each additional matrix that they said they solved.
The participants thought their work was anonymous but the researchers were able to go back and determine who had cheated by over-reporting the number of solved matrices. They discovered that night owls were more likely to cheat than larks.
In the second study the researchers asked participants to take part in a dice rolling test either early in the morning (7am-8.30am) or late at night (midnight-1.30am). They were asked to roll the dice and report the number back and were paid higher amounts for higher numbers.
The researchers found that larks in the night session reported getting higher rolls than larks in the morning session. In the same way, owls in the morning session reported getting higher rolls than owls in the night session.
The results tallied with the hypothesis that morning larks would behave more unethically in the evening, whereas night owls would do so in the morning, as these are the times when each group would be the most fatigued.
The researchers suggested that businesses could learn from their findings by allowing employees to work hours that best suit their circadian rhythms.
And from here, it appears that there's nothing wrong with getting a decent night's (or day's) sleep.
The findings will be outlined in full in Psychological Science later this year.