First-night effect explains difficulty sleeping in new environments

The ‘first-night effect’ describes a physiological brain response where individuals experience lighter, more interrupted, and shorter sleep when staying in an unfamiliar environment, such as a hotel or a friend's home. Research suggests that total sleep duration can decrease by approximately 20 to 30 minutes during this first night.

Scientists believe this phenomenon has evolutionary roots, serving as a survival mechanism. To protect against potential dangers in unknown settings, a portion of the brain—specifically the frontal lobe—remains more active and alert during sleep. This allows the body to react more quickly to unexpected stimuli.

While the effect can impact people of all ages, it appears most pronounced in children, adolescents, and the elderly, whereas individuals in their 20s seem less affected. Anxiety also plays a significant role, as the stress of being unable to sleep can create a cycle of restlessness. Other contributing factors include unfamiliar sounds, lighting, different bedding, and travel fatigue.