The expiation for a missed prayer is that you pray it immediately after you remember. I woke up after I missed Fajr. I literally lied on my bed for 3 seconds because I was tired but then remembered of it. Am I sinful for this and what would nullify the permission to make the prayer up ?

Ustadh AbdulAziz al-Haqqan

Don't pay attentuon to waswas