“Tidy (bed)room. tidy mind” is a popular saying, though not always an accurate one. “A tidy room is the key to a tidy mind” was cited in print in 1982.
 
A similar saying is “If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” “A cluttered up desk is the sign of a cluttered up mind” was cited in print in 1947.
 
“Tidy desk, tidy mind” has been cited in print since about 1948 and “Tidy house, tidy mind” since 1986.
   
 
Google Books
Wimps
Written by B. Sloane
Watertown, MA: Ivory Tower Pub. Co.
1982
Pg. 18:
A tidy room is the key to a tidy mind.
 
Google Books
Specialist in Love
By Sharon Wirdnam
New York, NY: Harlequin Books
2000, ©1991
Pg. 34:
A tidy room means a tidy mind — maybe the quality of his articles would improve, and then he’d be forever in her debt!
 
Google Books
April Brooker and Emily McLean
By John Dutch
Lincoln, NE: iUniverse, Inc.
2001
Pg. ?:
Unfortunately for Emily, my mother believes that the great secret of life is a tidy mind; and, as you might expect, a tidy mind is best achieved by a tidy bedroom; which means, amongst other things, that if you don’t wear it anymore, then we’ll soon find someone who will.
 
Daily Mail (London)
Feng Shui on the NHS income ‘tox’ and I’ll even make Derry Irvine sober as a judge
Quentin Letts
Last updated at 00:00 30 May 2003
(...)
Tidy room, tidy mind, tidy lifestyle: this has long been one of my philosophies. So I was disappointed, on dropping next door to see Gordon Brown, to find No 11 Downing Street filled almost to the ceiling with piles of paperwork.
 
Sys-Con Media 
Flexistore Invite Students to Enjoy Their Incredible Self Storage Prices!
BY MARKETWIRED .
NOVEMBER 30, 2010 01:00 AM EST
MANCHESTER, UNITED KINGDOM—(Marketwire)—11/30/10—Leading UK self storage company, Flexistore are currently promoting their amazing deals on self storage and as many students are now deep into their University life, there couldn’t be a better time for them to organise themselves.
(...)
The saying goes that a tidy room, means a tidy mind and the impact that decluttering your room in either student halls or a student house could have on their studies shouldn’t be underestimated.
 
OCLC WorldCat record
The tidy bedroom bible : tidy bedroom = tidy mind.
Author: Jen Annie McKay
Publisher: Sanity Books, 2011.
Edition/Format:   Book : English