Can you pass out in your sleep?

Yes. Always be sure to consume a normal amount of calories everyday. Not eating, besides depriving your body of calories and resulting in a low blood sugar level, can also cause a potassium deficiency, which can also cause dizzyness. Consult a doctor if you feel dizzy or passout. Not eating for the purposes of weight loss is unhealthy and could be the sign of an eating disorder. If you find yourself not eating for long periods, seek medical attention.