What the research suggests
Studies using slow-wave activity as a measure found that on the first night in a new environment, the left hemisphere showed deeper sleep than the right, interpreted as one hemisphere remaining partially vigilant — the so-called night-watchman effect. The asymmetry diminished on the second night. The finding is from small samples and should be held lightly, but the experience it describes is extremely common.
Practical contributors
Beyond novelty, hotels add specific problems:
- Rooms that are too warm — see best sleeping temperature.
- Unfamiliar noise: corridors, lifts, air conditioning, traffic.
- Light leakage around curtains.
- A different pillow and mattress.
- Travel fatigue with an activated nervous system — see jet lag.
- Alcohol, which is common when travelling and reliably fragments the night.
What helps
- Control light and sound. An eye mask and earplugs, or white noise from your phone placed away from the bed — see white noise.
- Get the temperature down before you get in. Most hotel rooms are set too warm for sleep.
- Bring something familiar. Your own pillowcase is small, cheap and genuinely helps, because the cue is partly olfactory and tactile.
- Do the same wind-down you do at home. A familiar sequence — even a five-minute version of the bedtime routine — signals to the system that the environment is safe.
- Arrive earlier if you can, so the room is not new at the moment you need to sleep.
- Skip the nightcap. It is the most common travel-sleep mistake.
If you travel often
Frequent travellers often develop conditioned arousal about the first night specifically — the anticipation of a bad night becomes part of the problem. The stimulus control rules apply here too: if you are awake for 20 minutes, get up rather than building the association further. And keep the same wind-down sequence regardless of location.
The second night
If your first night is bad and your second is fine, nothing is wrong with you. Plan important events for the second night where you can.