Stress is directly correlational to heart disease.
If you do experience palpitation or risk of high blood, I recommend you regularly check your blood pressure 3 times a day (morning, mid-afternoon, and evening)
Please note that I am not a doctor, but have been consulted by them after expressing concerns after prolonged periods of stress and lack of sleep due to overwork in both work and school/side-projects.
Note that your health and life is more important than work or that side project you are hustling on; and you should be able to ask for sick time off, if you need a health reset. I myself feared from taking time off because of fear of getting behind on projects; and it worsened my situation.
Be sure to work out regularly and maintain a relatively healthy life style.
Too much of anything is bad for you; work, success, and stress included.
If you are less than 30; which a lot of FAANG and startups prey on, then your tolerance to working long hours is pretty high.