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and disturbed sleep has many causative factors. Some major cause among them are growing age, any health issues associated like arthrittis spondylosis
, any emotional factor or anxiety
state of mind, restless leg syndrome
, any cardiac related disorder, any respiratory disorder, snoring
ettc. At the growing age the over all hormonal
synthesis and secretion get depressed as an aging process so that does not make a good sleep. Similarly any anxiety state of mind or over sensitive emotional natured person thinks little mater more seriously and that build up an anxiety state of mind. In the night during sleep those anxiety state exist at the subconscious state of mind and comes out during sleep. As you are telling of rapid pulse and takes deep breath so that could be the cause of anxiety state of mind. The second thing of any heart diseases . as you are telling of takes deep breath that because you need more oxygen. so need more more oxygen might be due to inadequate oxygenation result from lungs cant adequately expanding result from any heart related disorders or lungs related disorder. So to rule out this causes it is needed to go for an cardiology and pulmonology check up. If those things are ruled out then the only cause left is anxiety state of mind. If there is any cardiac related cause so the proper treatment is required. If the cause is anxiety related then anxiolytic medications with meditations, exercise, positive thoughts, some good homeopathic
medicines which are helpful also to cure anxiety condition all those will be helpful.