Sleep apnea is known as a night time breathing disorder, it increases a persons risk of having a heart atack or dyieng by 30 % over a period of four to five years. Sleep apnea triggers the body's 'fight or flight' mechanism, which decreases the amount of blood pumped to the heart. And decreases oxigen level into the brain. These type of suffrer’s brain activity become dull.
I am advising here some specific medi-yoga exercises which are helpful to reduce sleep apnea, heart atack, and specially increases oxigen level in the body.

Gomukh Asana;
gomukh asana is very beneficial for chest expansion.It icreases oxigen level in the body.you can see in asana list.  
Sit in vajra asana and place right leg above the left leg.  Extend the right arm up, turn the palm back, bend the elbow and hold the left palm which is placed behind the back.
Repeat it with others and hold for 30 to 60 second with slow, long and deep breathing.
Benefits; if it is practiced 5 minute daily, it help to reduce stress, tiredness, anxiety, breathlessness, backache and heart diseases.

Ustrasana;
this asana is also good for breathlessness. Breathlessness is one of the major cause for sleep disterbance. This asana increases prana lavel and spinal flexibelity.
Stand on both knee with little apart. Hold the right heel with your right hand, and left heel with left hand. Hold it for 2 minute with deep breathing. and then comeback to normal pose.    
  
Sarvang asana;
This asana help to increases blood  level in the brain. it releases endorphin level in the body. Decreases stress, tension and anxiety.
Lie flat on the back. Inhale and exhale deeply and slowly and relax whole body.
Now fold your both legs at knees, with support by your both hands (under hip and waist) raise lower part of the body and raise legs and spine until the toes point  to the ceiling. Keeps the spine and legs straight. In this pose breathing should be normal, concentrate on neck and head.
To come out of this posture, just bend your knees, curve your back and slowly return to lying on the floor while exhaling. First bend your knees, put the palms on the floor, then curving the spine, gradually unfold it the way one unrolls a carpet. When your entire back touches the floor, straighten the knees, take a deep breath and slowly lower your legs to the ground while breathing out.
Chest breathing; start breathing with chest, while you inhale chest should out and exhale with chest in. Do it for 10 minute.   

Step breathing; Sit in meditative pose, start step breathing in three steps.    

Anulom vilom;  
Anulom-vilom is on of the best exercise for balancing both right and left hemesphere of the brain. if it is practiced regularily, both hemesphere of brain could be balnced.
With closed eyes inhale deep and slow from left and exhale from right, again inhale from right and exhale from left. Do it alternatevly for 10 to 15 minute.  

Chaitanya Meditation;  at the end of all exercises, you should preferably do  chaitanya meditation.
Lie on the back comfertably, both hands and legs little apart. With closed eyes, let observe normal breath. do it for 5 minute.