16 year old terrified of not existing after death

Im a 16 year old who recently became very scared about the thought of death and not existing after death. I have a fair amount of anxiety, which I think could be influencing it. I'm healthy, active in sports and academics, and have loving parents and friends. Ever sense a random night a little over a week ago, death is all I can think about. The idea of not existing, not being able to think, or do the things I like, and not being able to feel after death terrifies me. I would love to believe in a religion or reincarnation, but I'm a fairly science based person, and don't think that an afterlife exists. These fears have affected my daily life, with randomly popping up when I'm out with my family or friends- it'll be normal at one point and then suddenly I'll feel like my days are numbered and at one point I will grow old and take my last breath, ceasing to exist. I have lost a lot of sleep, often not being able to fall asleep until 1 or 2am due to thinking and fearing death, which is problematic because I get up early to run. I know it's irrational to think about it at my age, but even after being distracted for a few hours I start thinking about death and often can't stop crying or panicking. I've done some googling on the internet and the process of cryogenics or freezing your body interest me, but I doubt the legitimacy of that and I think it makes me more freaked out. Any advice? Anything would be greatly appreciated