People now get one to two hours less sleep each night, on average, compared to 60 years ago. A primary reason for this is the proliferation of electronics, which also allows us to work (and play) later than ever before.
The Internal Revenue Service requires that individuals be able to produce records proving any income, deductions or credit claimed for at least three years from the date of a return, the statute of limitations for how long the I.R.S. has to assess additional tax if all income was reported correctly.
The Tax Department may ask you to provide copies of these records after you have filed your income tax returns. A paid preparer must keep a completed copy of the return for each taxpayer for three years. Also see Publication 58, Information for Income Tax Return Preparers.