Always sleepy during the day & at night when i wake out of sleep & change positions, my heart starts beating really fast & sometimes irregular, worry?

Fatigue: There may be different causes to your problem. Obstructive sleep apnea is more commonly recognized now and can be responsible for daytime sleepiness, fatigue and heart palpitations due to lack of oxygen tissue perfusion. Irregular heart beats (arrhythmia) caused by a heart problem per se may be another reason. Both need to be assessed and worked out appropriately.