Why do we often struggle to sleep well the first time we stay in a new place? This is called the First-Night Effect, a common experience where the first night in an unfamiliar setting disrupts our sleep. While we usually sleep better on the second night, it's not clear if this improvement happens when the nights are days apart. Researchers at the University of Fribourg are exploring whether the unfamiliar environment or other factors cause this initial restless sleep.

Many people find it hard to sleep well the first night in a new place, a phenomenon called the First-Night Effect (FNE). In this newly published study in the journal Sleep and funded by the European Research Council (ERC), Professor Björn Rasch and his team at the University of Fribourg explored what happens if we return to the same place a week later.

The First-Night Effect persists
The research involved two separate studies with healthy young adults. In the first study, 45 participants slept in the University of Fribourg’s sleep lab for two nights, with a week in between. In the second study, 30 participants also slept two nights in the sleep lab and two nights at their own homes, again with each night a week apart. Researchers used a mobile electroencephalogram (EEG) to monitor brain activity and asked participants to fill out sleep quality questionnaires each morning.

The findings showed that the FNE still happens even when the nights are not consecutive. PhD student Anna Wick from the Department of Psychology and Björn Rasch found out, that partici-pants had trouble falling asleep and staying asleep, and overall, slept less on the first night—whether at home or in the lab. A week later, sleep quality improved, but sleep was generally bet-ter at home than in the lab.

Exploring the role of deep sleep
There’s a new theory that on the first night in a new place, one half of the brain stays more alert to potential dangers, leading to lighter sleep on that side. However, this study found that asymmetric sleep patterns occurred every night, not just during the FNE, and were not affected by how familiar the environment was. This suggests that the uneven sleep depth could be more about individual traits than the environment.

Situational and environmental adaptation of sleep
The researchers concluded that both the unfamiliar environment (like a new room or bed, unfamiliar noises) and the situation (like being connected to recording equipment) can affect sleep quality. This is why spending more than one night in a new place is advisable. Anna Wick suggests, “If you're planning a trip, try to stay more than one night or return to places where you've already slept.”

Study
Wick, A. Z., Combertaldi, S. L., & Rasch, B. (2024). The First-Night Effect of sleep occurs over non-consecutive nights in unfamiliar and familiar environments. Sleep, zsae179.