Insomnia is a common sleep disorder that affects millions of people around the world. It can cause a range of symptoms, including difficulty falling asleep, staying asleep, or waking up feeling unrested. Insomnia can be caused by a variety of factors, including stress, anxiety, depression, pain, and certain medications. It can also be a symptom of underlying medical conditions, such as sleep apnea, restless leg syndrome, or narcolepsy. If you're struggling with insomnia, it's important to understand the underlying cause in order to find the best solution for you.