根据以下材料，回答{TSE}题
Insomnia, or "poor sleep",can have bad effects on a person´s health and general well-being. It can 21onboth our physical and mental health and can lead to other health22
Insomnia can be traced to many different reasons,but what is 23to ninny sufferers is their inability to relax fully and "switch the mind 24Constantthoughts,25 around and around in the mind, moving from one 26 tothe next, prevent stillness and peace and 27 a sufferer extremely tired.
In order to treat insomnia 28, it isfirst
necessary to allow a sufferer tore-experience 29 real
relaxation feel like.It’s almost as though they´ve forgotten how to relax. Once this hasbeen 30 by the brain, then fast and effective 31 can be made to reeducatethe unconscious towards allowing the person to relax 32 and to allow anatural state of sleep
to33
Hypnotherapy(催眠疗法) is one of the fastest and
most effective ways of 34 this goalfor long-lasting results.
Sleeping pills, if used at all, shouldonly be a short-term35as their effect is soon reduced and their side effectscan be deep and far-reaching.
{TS}第21题答案是（　　）

A harm

B affect

C change

D impact