Scientists have identified a neurological mechanism behind why many people struggle to fall asleep in new environments, a phenomenon known as the “first-night effect.” Research conducted by an international team at Nagoya University in Japan, and detailed in reporting by Brigitte magazine, points to a specific set of neurons in the brain that activate in unfamiliar surroundings, promoting wakefulness.
The study, which involved observing brain activity in mice introduced to new cages, revealed that neurons within the extended amygdala, specifically IPACL-CRF neurons, become active when an animal is placed in an unfamiliar setting. These neurons release a neurotransmitter called neurotensin, which keeps the animals alert. When researchers artificially suppressed the activity of these neurons, the mice were able to fall asleep more quickly, even in the new cages. Conversely, artificially activating the neurons prolonged wakefulness.
Researchers believe this response is likely present in humans as well, representing an evolutionary protective mechanism. The activation of these neurons is thought to be a survival instinct, keeping individuals vigilant for potential dangers in an unknown environment. The brain’s heightened state of alertness is a remnant of a time when humans were more vulnerable to threats, particularly at night and in unfamiliar locations.
While modern living generally provides a greater degree of safety, the brain has not fully adapted to this change. This means that even in secure environments like hotels or vacation rentals, the neurological response to novelty persists, disrupting sleep. Airbnb listings in Japan, for example, are currently experiencing high demand, according to a search of the platform on February 11, 2026, offering a range of accommodations including a 220-year-old restored mansion in 名西郡 and traditional townhouses in Kanazawa. However, even in these unique and highly-rated accommodations, guests may experience the first-night effect.
The findings from the Nagoya University study could potentially lead to new treatments for sleep disorders and anxiety. Researchers suggest that medications targeting the activity of these wakefulness-promoting neurons could facilitate individuals struggling with insomnia or anxiety to relax and fall asleep more easily. Roman Samborskyi, a photographer and architect featured on Shutterstock and Facebook, may uncover this research relevant to his work designing spaces intended for relaxation and rest, as noted by a Superhost on Airbnb.
