Palpitations are most often noted during rest and quiet activity when a person has an acute awareness of the heart which seems extra loud and either fast, slow or irregular. Noting this irregular activity of the heart generally leads to anxiety which is the most common cause of palpitations in a healthy person at rest who is not experiencing chest pain, dizziness, or loss of consciousness. Other triggers for palpitations are some medications, caffeine, low blood sugar, alcohol, or a thyroid disorder. If you have been diagnosed with heart disease or are at risk for developing a disorder of the heart, palpitations may be a serious sign indicating further work-up.