Atwater was born in Twin Falls, Idaho and was later adopted by Kenneth L. Johnston. She married John Bernard Huffman in 1956 (divorced in 1976) and had three children: Kelly, Natalie, and Pauline. She became a secretary, and a prize-winning cook at the Twin Falls County Fair.

It was because of a hand-writing analysis in the mid-sixties that Atwater ever became a writer. She was hired as Staff Writer for the Idaho Department of Commerce and Development (1969-1971), free-lance assignments for Sunset Magazine, staff writer for Incredible Idaho Magazine. She was awarded "Most Influential Newspaper Columnist in the State of Idaho" by the Idaho Statesman, and given the Governor's Meritorious Wage Increase for Outstanding Service to Idaho. She developed the statewide program for Boy Scouts and Girl Scouts to give tours of the Idaho Capitol Building and Supreme Court as points for badge awards, and wrote their scripts. As President of the Boise Chapter of the Idaho Writers League, and later as First Vice-President and then President of the Idaho Writers League, she was named "Prose Writer of the Year." A member of Idaho Press Women, she won numerous awards and commendations. She later excelled in Shopping Center Promotions and won "Most Outstanding Low-Budget Shopping Center Promotion in the Nation" award. She has worked as Director, Legislative Public Information Center, for the House of Representatives, Idaho Capitol Building. She has been a Forms Analyst for the Idaho First National Bank (central management), later as their Technical Manuals Writer.

She created and incorporated Inner Forum, Idaho's first metaphysical non-profit, edited the Inner Forum Magazine, and launched the Northwest's first speaker's bureau on metaphysical topics. She helped to initiate and produce Idaho's first conference on The Arts and Governor's Bi-Annual Awards for the Arts. Since 1966, she has been an active investigator and researcher of psychic phenomena and altered states of consciousness, was a hypnotist for six years, taught practical numerology for several decades, and became a member of the American Federation of Astrologers. She is also a long-time professional member of the Authors Guild and the Authors League of America.

Because of extreme health reversals, Atwater left Idaho and moved to Virginia. Atwater married Terry Young Atwater in 1980.

Atwater is one of the original researchers in the field of near-death studies, having begun her work in 1978 (shortly after moving to Virgnia), and is a pioneer in subjects like near-death experiences, the aftereffects of spiritual experiences, transformations of consciousness, reality shifts, future memory, and modern generations of children and how they differ from previous generations. Atwater did free-lance assignments for many periodicals nationwide including Sunset Magazine. She wrote the column "Coming Back" for the Vital Signs magazine 1981 - 1985. She earned her Letters of the Humanities (L.H.D.) doctorate from the International College of Spiritual and Psychic Studies in Montreal, Quebec, Canada, May 19, 1992; and was awarded an honorary Ph.D. in Therapeutic Counseling in March 2005, from Medicina Alternativa Institute, The Open International University for Complementary Medicines, in Colombo, Sri Lanka. Also in 2005, the International Association for Near-death Studies (IANDS) presented her with an Outstanding Service Award and the National Association of Transpersonal Hypnotherapists awarded her a Lifetime Achievement Award. She has been a Prayer Chaplain since 2004.

Atwater retired as an active fieldworker in near-death studies in 2010, calling for the entire field to recognize near-death states as part of the larger genre of transformations of consciousness and how they change people. Her last book on this subject, which gives her summation, is Near-Death Experiences: The Rest of The Story (Hampton/Red Wheel, March, 2011). For the first time, she wrote the entire story her own three near-death experiences (I Died Three Times in 1977 - The Complete Story) published as an e-book in August, 2010.

Atwater is a noted authority on near-death experiences (NDEs), especially on the after-effects of NDEs, on NDEs in children and on hellish NDEs. She experienced three NDEs herself and has interviewed over 4,000 adult and child near-death experiencers. In 2001, her work on NDE after-effects was cited in The Lancet. As a result of her writings, she has been invited to speak around the world.

In Future Memory (1999), Atwater proposed a new theory of reality that describes the way in which we are able to envision the future in a way that is like a memory, where people can live life in advance. Atwater described how these rehearsals for future events differ from other modes of futuristic awareness such as clairvoyance, precognition, and déjà vu. In this book, Atwater was the first to use the term reality shift.