Several studies have shown that people who sleep earlier are healthier compared to those who work nightshifts or are night-owls. People who fail to catch enough deep sleep have a higher chance of living with diseases like type 2 diabetes, heart disease, and hypertension. Researchers also found that the phase of deep sleep between 10 p.m. and 2 a.m. is really important for our immune cells. People who had no deep sleep had a lower virus antibody response, meaning that they could get ill easier.