Excel 2007 : Cell to display "Night Worker" or "Day Worker" from Date Time

I have a spreadsheet with 1,000 records of data that has 10 columns, one being (Time Started) with date and time (2/15/2010 9:34:31 AM).

I want to display in another new column (Processors) “Day workers” or “Night Workers” from the spreadsheet’s (2/15/2010 9:34:31 AM) data. I would desire 7am to 3:30pm “Day Workers” and all else “Night Workers”.

I attempted to use the formula “IF(AND(HOUR(NOW())>=7,HOUR(NOW())<=16),"Day Workers","Night Workers")” in a post recorded already, but it will only displays “Day Workers”. I am attaching my spreadsheet for clarification.