The time of day could be correlated with how honest you are. If you're just waking up, you're more likely to tell the truth compared to later in the day. It's called the morning morality effect.
A Harvard University study finds that our ability to tell the truth diminishes towards the end of the day. Research suggests that the self-control needed to tell the truth fades throughout the day because we get tired. Lying becomes a little easier even if you're typically an honest person.
In one study, groups of young men and women were shown pattern of dots on a computer. One side of the screen (left vs right) had more dots than the other side. The volunteers had to tell the computer which side had the most dots. They were given 10 times more money for choosing dots on the right side, whether it had more dots or not. Those who played in the afternoon were more likely to keep fibbing and choosing the right side.
A second experiment tested if respondents could be primed with words related to morals. For example, word completion tasks like E_ _ _C_ _ and _ _ RAL were shown. People in the morning were more likely to see ETHICAL and MORAL, whereas people in the afternoon tended to see neutral words like EFFECTS and CORAL.
And these effects were most pronounced in people who prided themselves on being honest, the study says. It seems, according to the study authors, that humans have a gradually depleting self-regulatory process.