Hi, thank you for using health care magic for your health related quarry. I can understand your concern. As cardiologist reported heart is healthy next possibility to ruled out is thyroid function. Many times elevated thyroid hormone level can also produce this symptoms. If this is also normal then treating Anxiety is next step in managing your symptoms. You also reported you are suffering from depression and anxiety that suggest the possibility of panic attack on that night. Panic attack is an episode of anxiety for around 15 to 20 minutes with symptoms of chest pain, palpitation, breathlessness, tremor,uneasiness etc. Medicines like sertraline, escitalopram, peroxetine, venlaflxine are useful in both depression and anxiety. They are also useful for panic attacks. Drug like clonazepam can be useful for as and when required during attacks. Other method of treating these disorders are psychotherapy like cognitive behavioral therapy. This can be used alone or as add on to drugs. I hope my answer will help you. Regards.