Adrenaline

Adrenaline is a perk in Fallout 4.

Effects
Adrenaline is a perk that is granted when playing on Survival difficulty. It provides a bonus to damage output and is increased by getting kills. Every five kills increases your Adrenaline rank, adding 5% bonus damage. A maximum of 50% extra damage can be built up at rank 10 of the perk.

Sleeping in a bed removes anywhere from 2 to all 10 ranks of Adrenaline, depending on the time you've slept.