It is a jarring experience to be drifting off to sleep or just waking up and hear a clear, distinct sound, such as a doorbell ringing or a phone chirping, only to realize the sound was entirely in your head. This phenomenon is surprisingly common and often leads people to wonder if they are fully awake or if their hearing is playing tricks on them. This startling occurrence is a temporary quirk of the brain’s transition between sleep and wakefulness, not a sign of a hearing problem.
The Science of Hearing Sounds During Sleep Transitions
The experience of hearing sounds that are not physically present during the transition into or out of sleep is known as a sleep-related auditory hallucination. These hallucinations occur because the brain is caught in a mixed state, partway between being fully awake and fully asleep.
When the sounds occur while falling asleep, they are called hypnagogic hallucinations. If they happen as you are waking up, they are termed hypnopompic hallucinations. In both cases, the brain generates sensory input without external stimulation, often involving common environmental sounds like a doorbell, a voice, or a knock. This happens because the brain’s control mechanisms, which separate the waking world from the dream world, are momentarily out of sync, allowing elements of the dream state to intrude upon consciousness.
Common Triggers That Cause Auditory Hallucinations
These auditory hallucinations are harmless and often linked to temporary lifestyle factors. One of the most common triggers is a lack of sufficient sleep or an irregular sleep schedule, which destabilizes the brain’s normal sleep-wake cycle. When the body is sleep-deprived, the brain is more susceptible to these transitional phenomena as it struggles to regulate its state.
High levels of psychological stress and anxiety also make the brain more prone to generating these sounds. Worry and emotional distress can heighten overall brain activity, making the transition between wakefulness and sleep less smooth. This heightened state of alertness can lead to a misfiring of sensory neurons, resulting in a perceived noise.
Certain medications or substance withdrawal can also increase the frequency of these hallucinations. For example, abruptly stopping medications like selective serotonin reuptake inhibitors (SSRIs) or benzodiazepines can affect the neurochemical balance that regulates sleep. These changes likely interfere with the brain’s ability to transition cleanly through the stages of sleep. Prioritizing consistent sleep and managing stress can often reduce the occurrence of these startling sounds.
When Doorbell Sounds May Indicate a Larger Sleep Issue
While these hallucinations are typically benign, their frequent appearance can be a symptom of a deeper, diagnosable sleep disorder. The most notable connection is with narcolepsy, a neurological disorder that affects the brain’s ability to control sleep-wake cycles. In people with narcolepsy, the rapid eye movement (REM) sleep stage can intrude into wakefulness, often manifesting as hypnagogic or hypnopompic hallucinations.
If the sounds are intense, occur frequently, and are accompanied by other specific symptoms, a consultation with a doctor or sleep specialist is advised. Warning signs include excessive daytime sleepiness, which is an overwhelming urge to fall asleep during the day. Other indicators are sleep paralysis (the temporary inability to move or speak upon waking or falling asleep) or cataplexy (a sudden loss of muscle tone often triggered by strong emotions). The presence of these combined symptoms suggests a need for professional evaluation to determine if a condition like narcolepsy or severe sleep apnea is the root cause.