We’ve all had to pull an all-nighter for school or work (or maybe an occasional Netflix binge), but according to new research, missing out on sleep can actually damage your brain. By studying mice who slept regularly and others that were kept awake, researchers found evidence of brain cell damage in the non-sleeping subjects. The research also calls into question the idea of “sleep debt”—meaning you can’t really “make up” sleep because the damage is “irreversible.” Though the team from UPenn’s Perelman School of Medicine hasn’t reproduced the test on humans, the study author told US News, “You’re at a time in your life when you really have to pull a couple of all-nighters to sustain that edge academically or professionally, but by cutting our sleep times short then do we end up losing that edge in the long term because we lose those neurons that are so critical for attention?” Just something to think about next time you want to stay up until 5 in the morning watching The Walking Dead …