How can I find the prevalence of shift workers in the United States in 2012 and 2013 using this database?

I am conducting a research project in which I want to find the prevalence (or percentage) of shift workers in the United States, preferably for 2012 and 2013. Not just night shift workers, but shift workers in general. Can I do this on the ATUS database?

There is quite a bit of information on work status available in the Time Use Survey data (see the full list here). However, there is no direct identification of shift workers. So, although there may be a reasonable way to indirectly identify shift workers, I am not aware of how this could be done. OCC and OCC2 provide the detailed and general occupation codes, respectively. The CLWKR identifies the type of job an individual has. Perhaps these variables will be helpful to you.

A possible alternative is to use data from the Work Schedules Supplement form the CPS and link these records to the Time Use file. The variable WSOTHSHFT identifies the usual shift schedule of the primary job if the respondent does not work a regular daytime shift (e.g. within the hours of 6am-6pm). A limitation for this approach is that the Work Schedules Supplement is only currently available in 1997, 2001, and 2004 and therefore only overlaps with IPUMS Time Use samples in 2004.