There are millions of old wives tales explaining how soldiers, Marines, airmen or sailors keep themselves awake. The military is the one place where you can count on sleep deprivation of all sorts, from the heavy eyelids of a 24 hour CQ or Staff Duty shift, to the directly imposed deprivation of SERE school. The point of all of this deprivation isn’t just to see if you can stay awake — you have to actually perform (at a high level of function) under these conditions. However, keeping those eyelids from shutting is the first step.

So how do they do it?

Here are a few methods I’ve tried:

Physical exercise. This works really well — your sluggish body and soul perk back up, your eyelids flutter open and you’re back on point again. However, the downside to this is that for every minute of energy you gain, you lose two. The short-term results work well, but the long-term? Now you’re even more tired than when you started. Conserving your energy is important, especially in the SOF world — not to mention you can’t exactly run around and do jumping jacks if you’re on a block position in the middle of Afghanistan.

Slapping yourself. SLAP! You wake up. You start to fall back asleep. SLAP! You wake up. You start to fall back asleep. Slapping, pinching, or other forms of “self harm” works in the very, very short-term. If you’re in this situation to begin with, you’re probably suffering enough physical abuse that a little slap or a pinch is not likely to affect your body and mind much.

Engaging mentally in something. If whatever you’re doing is mundane (staff duty, pulling security), then getting up and engaging in a physical action can be quite helpful. That could mean mopping the floors or going around and checking everyone’s sectors of fire (even if you’ve already done this, it’s for your benefit not theirs). The problem with this one is that you’ve probably been tasked out with something specific, and it’s unlikely that you’re going to be able to deviate from that tasking a whole lot.

Caffeine. The obvious choice. It works, if you have access to it. However, I’ve found that there is a point of diminishing returns once you start getting past the first 24 hours. The effectiveness, while still present, drops off significantly after a certain period of time. It’s also not always readily available.