Yes, it is possible for people to make sounds in their sleep without realizing it. This phenomenon is known as "sleep talking" or "somniloquy." Sleep talking occurs during different stages of sleep, most commonly during the transition between non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep.
During REM sleep, the brain is highly active, and vivid dreams can occur. Sleep talking can be a result of vocalizing dream content. It's important to note that sleep talking can also happen during NREM sleep, which does not involve dreaming.
In most cases, sleep talkers are unaware of their vocalizations because they are asleep. However, there are instances where people may partially wake up while sleep talking, becoming briefly aware of the sounds they make. They may quickly fall back asleep and have no recollection of the event upon waking up.
The sounds produced during sleep talking can range from murmurs and mumbles to clear and coherent speech. Sometimes, the speech may be nonsensical or fragmented, reflecting the dream content. In other cases, sleep talking can involve complete sentences or conversations.
It's important to note that sleep talking is generally harmless and does not indicate any underlying medical condition. However, if sleep talking is accompanied by other sleep-related issues, such as frequent nightmares, excessive daytime sleepiness, or disrupted sleep patterns, it may be worth consulting a healthcare professional to rule out any potential sleep disorders.