A middle-aged bureaucrat has collected data on his sleep pattern for 29 weeks or so. He works 4 days a week (not Wednesdays) and wants to know whether these data should impel him towards early retirement. We can see from the above that the prospect of going back to work on Monday and Thursday causes some lack of sleep.
Table of sleep data
The overall mean is 06:29, while results here indicate an average of 06:50 for those aged 40-55. The difference is hardly large, but in the other hand the justified expectation of sleeping poorly tw0 nights a week is not something one would wish to continue indefinitely.
We presume that there are essentially two possible explanations for the smaller amount of sleep on Sunday and Tuesday nights: apprehension and having to get up early/change in routine. If it was purely a case of the latter, we would expect the effect to be greater on a Sunday night since there are two days of changed routine to account for as against one on a Wednesday night. But in fact there is no significant difference between the means for Wednesday and Sunday, so we presume apprehension is playing a role here.
Our preliminary recommendation would be for the client to collect the same data for a substantial period of leave so as to establish how far the results above deviate from the natural pattern. And here it is!