Answers:
It could be like mad of things...
Bad dream
Hypopnea (low oxygen horizontal, related to apnea)
Sleep apnea
Waking up suddenly (e.g. phone ringing, alarm clock)
Either approach, if it bothers you or happen on a regular proof, stir see a doctor.
ask doctor!
have your doctor check for hyperthyroidism. well brought-up luck.
you might own sleep apnea - the loss of breath during some stages of sleep. your body compensates by letting your heart pump double or possibly even thrice when you gain into apnea.
sleep apnea is usually cause by an impediment close to enlarged adenoids, inflammed nares, etc, so progress see an ENT for this.