All income from all sources worldwide must be reported on a US tax return.  And more income does increase your AGI  and may be used for mortgage purposes... ask your underwriter/mortgage broker. 

Of course if you are applying for a mortgage they really want to know about your net worth (what you have in the bank making the interest) not just the income on the account.

Unless you have a large amount of money in savings, the annual interest is probably small compared to your total income.

Have you not been reporting bank interest income?

Note that your bank is required to issue a 1099-INT if they pay more than $5 of interest, and the IRS gets a copy, which your mortgage broker may review.  If you have failed to claim interest, the IRS should be sending you a bill for income tax due.  If you try to claim more interest than you actually earned on your mortgage application, that may show up when the underwriter reviews your past tax returns.