I don’t do well in the cold. I’m the kind of person who wears sweatshirts in the desert summer (I’m not kidding) because my body believes it’s in Antarctica. Camping, while I love it, has always been a struggle because sleeping is something that only really happens when you’re comfortable….and having my entire body shaking from the cold like I’m having a seizure isn’t what I define as comfortable. 
I recently discovered a sleeping bag liner; a little cotton sack that you place inside of your sleeping bag when camping. Placing a liner inside your bag provides a layer of insulation to help you stay at a comfortable temperature on cold nights. It adds an additional 10-20 degrees of warmth!!! I took one with me to the top of a mountain (where, typically, it gets rather chilly).
It was like a blanket on a bed. I slept like a baby!! No shivering, no shaking, no waking up wondering if I’m alive or in the tundra. Those few extra degrees were the difference between me enjoying the trip to me not enjoying the trip, but those precious degrees could mean a lot more if the situation was different.
When it comes to emergency preparedness, a few degrees can mean life or death. It could mean freezing or it could mean surviving. Sleeping bag liners are cheap, light, and efficient. Whether camping, backpacking, or preparing a 72-hour kit, a liner is something I highly recommend. If you’re a summer-baby like me and need to have 10 blankets and 3 jackets on (okay, maybe that’s an exaggeration) then come by and grab one! It’ll save you! If you’re preparing for an emergency then come by and grab one! It could save you!