Martin Lee, the Threat Intelligence Technical Lead over at Cisco, posted a fascinating article about the dangers of clicking on links when tired. There has recently been a campaign telling people that driving tired is as bad or worse than driving drunk, and now it seems that clicking tired is also on the track of bad things to do.
The study isn't exactly scientific, for example it compares the number of websites visited during the day against the number of known malicious sites during the day. They are showing that the number of malicious links clicked on definitely rises during the night and then diminishes again during work hours.
There are many conclusions that could be made as to why this happens, perhaps people are more apt to engage in risky Internet usage when they aren't at work. Perhaps this maps to when children are in school and don't have access to computers. Maybe the majority of emails with malicious links in them get sent during the night and are available first thing in the morning (the highest peak of malicious sites was around 5-6am).
It is still an interesting and compelling study, though, because it definitely shows a trend. My advice, be mindful of when you make good and bad decisions with computing. Always think about what you are doing, and if you aren't in a mindset to think clearly (tired, inebriated, distracted, driving), then put down the mouse and find something else to do.