Feeling fearful or anxious upon waking from a nap can be due to various reasons, including:
Sleep Inertia: This refers to the groggy, disoriented feeling you might experience right after waking up. It can be more intense after a nap, especially if you wake up during a deeper stage of sleep.
Sleep disorders: Certain sleep disorders, like sleep apnea, could cause you to wake up feeling anxious due to periods of not breathing that occur during sleep, leading to sudden awakenings. Another sleep disorder, known as sleep paralysis, could also induce feelings of fear, as it involves being unable to move or speak when falling asleep or waking up.
Anxiety or stress: If you are going through a particularly stressful period or if you have an underlying anxiety disorder, these feelings could manifest upon waking from a nap. In fact, anxiety can also lead to nightmares, which might lead to feelings of fear upon waking up.
REM Sleep: During Rapid Eye Movement (REM) sleep, your brain is often active with vivid dreaming. If you wake up during this stage, especially from a dream that is intense or frightening, it could result in feelings of fear or anxiety.
Hypoglycemia: Low blood sugar, or hypoglycemia, can occur if you haven't eaten for a while, which is often the case when you take a nap. Symptoms can include feelings of anxiety or unease.
If this is a regular occurrence and is affecting your quality of life, it would be wise to consult a healthcare provider. They might refer you to a sleep specialist, or suggest lifestyle changes, therapies, or treatments based on your specific situation.