Sleep talking (also know in the sleep field as "somnliloquy") is a sleep disorder that involves unconscious talking during sleep. Sleep talking varies in its content and presentation, ranging from mumbling, gibberish and nonsensical words to full, complicated, coherent narratives. Sleep talking can be spontaneous, but may also be induced by someone else who talks with them while asleep. This nocturnal language can even sound different from their wakeful speaking voice!
Although anyone can experience sleep talking, it can be genetic and tends to occur more in males and children. Sleep deprivation, alcohol and drugs, fever, stress, anxiety and depression can all lead to episodes. Sleep talking is commonly seen in the context of other sleep disorders, especially parasomnias (e.g. night terrors, confusounal arousals, sleepwalking), sleep apnea and REM behavior disorder. Sleep talking that starts spontaneously after the age of 25 is often seen along with other medical or psychiatric issues. In severe cases, sleep talking may be associated with nocturnal seizures.
The content of sleep talking can be completely random but may also be related to past or present daytime experiences. Decoding it may be impossible (or not even necessary). Since sleep talking happens outside of conscious awareness, it isn't even admissable in a court of law.
Sleep talking can happen at any time during the night and during any stage of sleep. In the earlier part of the night, people tend to be more in the deeper stages of sleep (Stage 3/4) and sleep talking may sound more like gibberish or mumbling at that point. As the night progresses, sleep becomes lighter (REM sleep and Stages 1 and 2) and may be more understandable to a bed partner.
Sleep talking is not physically harmful, but can be very embarrassing for the patient. In addition, it can be an annoyance to anyone nearby who is trying to sleep. Patients who sleep talk may even avoid sleeping in the presence of others for fear that it might disrupt someone else's sleep.
For most, sleep talking is a short-lived phenomenon that is benign and doesn't require any treatment. However, if it is happening multiple times per week and/or disrupts a bed partner's sleep, consider talking with a sleep specialist to rule out any other underlying medical or psychiatric disorder that might cause or exacerbate the problem. Regardless of the frequency, following proper sleep hygiene (e.g. keeping a regular bed and wake time, obtaining adequate sleep every night, avoiding alcohol and tobacco at night, avoiding caffeine from the afternoon onwards) and minimizing stress and anxiety is all helpful and can reduce events.
Bed partners may also find that silicone earplugs or a white noise machine (or even a fan) can help reduce the noise. If sleep talking creates a significant amount of insomnia for a bed partner, sleeping in separate rooms until the sleep talking is better controlled may be advised. Better sleep at night will lead to less frustration between the couple and better mood overall.