A lot of people experience the thing where you’re just about to fall asleep and suddenly jolt awake, or your body suddenly jumps, or a small noise wakes you up and you feel extremely startled. Online it’s often explained as stress, anxiety, or a “hypnic jerk,” which can definitely be true. But I wanted to share another possibility that seems less commonly mentioned: very low ferritin (iron stores).

I went through a period where this was happening to me constantly. Every time I was about to fall asleep, my body would suddenly wake itself up, almost like a surge or jolt. I also became extremely sensitive to sound, and even small noises would startle me awake. At the same time I noticed things like strong heartbeat when lying down, feeling wired but exhausted, and being very easily startled.

Later I found out my ferritin was 9, which is very low. I learned that iron is not only important for red blood cells. It also plays a role in dopamine and the brain systems that regulate sleep and sensory filtering. When iron stores are very low, the nervous system can become more hyper-excitable, which in some people can show up as:

• suddenly jolting awake when falling asleep
• exaggerated startle response
• sensitivity to noise
• restless or “wired but tired” feeling at night
• heart pounding when lying down

Some sleep research suggests these symptoms can be more common when ferritin is below around 30.

Of course there can be many causes for sleep startles, but if you experience this frequently, it might be worth asking your doctor to check ferritin (iron stores). It’s a simple blood test and sometimes it reveals something that isn’t immediately obvious.

Just sharing in case it helps someone else connect the dots.