Insomnia

You are describing a pattern of awakening that is suggestive for the condition, "obstructive sleep apnea."

This condition results when your airway tissues collapse together to close your airway as you enter deep stages of sleep. A drop in your oxygen results since you are not breathing effectively and this shortage of oxygen creates an alarm signal in your brain (a rush of adrenaline). You are awakened by the rush of adrenaline and your airway quickly reopens.

Obstructive sleep apnea is a dangerous condition when it is not treated. Repeated drops in your oxygen supply may result in heart failure. Persistent elevation of your body's adrenaline hormones may cause hypertension (high blood pressure).