Why am I falling asleep when I meditate?

My main struggle while meditating are distractions.

Vicious circle.

I always think of something, catch myself think then remember not to think and I’m already thinking of something else.

It’s complicated, but whenever my thoughts become less agitated, I always start falling asleep. I feeling myself getting heavier then I “wake up”.

It’s weird because I’m not tired but every time my mind is kind of at rest with my thoughts, I find myself falling asleep.

Do you have any trick or observations on this!?

Thank you.