Summer Travel: Why the First Night Away Feels Different

Last updated: October 2026

The first night in a new place is often lighter and more broken, and lab research suggests why: on the first night in an unfamiliar setting, one side of the brain slept less deeply and responded more to unexpected sounds, a pattern that disappeared on later nights (Tamaki et al., 2016). A follow-up study of 24 adults replicated the effect (Tamaki & Sasaki, 2019). Below is what those studies found, what changes when the pillow changes, and how the Pillowise Travel size fits nights away from home.

Key takeaways

On a first night in an unfamiliar setting, one brain hemisphere slept less deeply and reacted more to unexpected sounds, a pattern gone on later nights (Tamaki et al., 2016).
A follow-up study of 24 adults replicated the first-night pattern in non-REM sleep (Tamaki & Sasaki, 2019).
A Pillowise fitting takes three measurements (shoulder width, neck circumference and neck length) and adds sleeping position and bed type to choose from seven sizes.

Why do people sleep worse the first night away?

Sleep researchers have long seen poorer sleep on a person's first night in a sleep lab, and call it the first-night effect. A brain imaging study looked at where it comes from (Tamaki et al., 2016).

On the first night, deep sleep was uneven between the two halves of the brain in one network. The larger the imbalance, the longer people took to fall asleep. The less deeply sleeping half responded more to unexpected sounds and produced more arousals and faster reactions, and these differences were gone in later sessions.

The authors read this as one half of the brain keeping watch in an unfamiliar place. It was a small lab study, and the "night watch" explanation is their interpretation.

Does the effect show up in every stage of sleep?

A follow-up study of 24 adults replicated the uneven deep sleep in non-REM sleep but did not find it in REM sleep (Tamaki & Sasaki, 2019).

During REM sleep on the first night, both halves of the brain were more alert to sounds. The authors concluded the brain stays watchful in a new place through more than one route.

What changes when the pillow changes?

A hotel or guest room also means a different pillow, and pillow height changes the neck in ways that can be measured. In a radiographic study of 16 adults, raising the pillow from 0 to 10 to 20 cm increased T1 slope and C2-7 Cobb angle while neck tilt decreased (Kim et al., 2015).

A crossover study of 10 healthy participants paired with finite element modeling measured how heights from 110 to 170 mm shift pressure across the head and neck (Ren et al., 2016). In a pilot EMG study of 15 adults lying on their side, the height matched to shoulder width produced the lowest neck and shoulder muscle activity (Jiao et al., 2025).

Why do generic pillows miss?

A standard contoured pillow, not fitted to the individual, performed no better than ordinary shapes in a randomized study of 106 side sleepers (Gordon et al., 2009). No single optimal pillow height can be specified, because it depends on four variables that differ from person to person: cervical alignment, body dimension, contact pressure, and muscle activity (Lei et al., 2021).

What we measure

Pillowise is a fitted cervical pillow that licensed healthcare providers measure and dispense, made in seven sizes.

Our sleep specialists take three measurements: shoulder width, neck circumference, and neck length. Combined with sleeping position and bed type, an algorithm identifies the best-fitting pillow from seven sizes.

Shoulder width is the measurement the EMG study found mattered most. A height matched to it produced the lowest neck and shoulder muscle activity during side sleeping (Jiao et al., 2025), and body dimension is what drives the individual optimum (Tian et al., 2025).

A systematic review of 11 studies covering 309 participants identified a 7 to 11 cm unloaded central height among the parameters supporting spinal alignment and sleep comfort (Radwan et al., 2021). The size is chosen from those three measurements plus sleeping position and bed type, rather than from a single stock height.

The Pillowise Travel size is measured the same way as the Standard and Queen, in a smaller format to take with you on nights away from home. Pillowise pillows are made from premium Dutch memory foam and certified to OEKO-TEX Standard 100, meaning every component has been tested against the standard's limits for harmful substances.

Scope

The first-night studies were small lab studies of brain activity, not studies of pillows or hotels. No study has tested whether bringing a familiar pillow reduces the first-night effect, and we make no such claim. The pillow studies are small, and the most recent systematic review found no clear advantage for any pillow type in chronic neck pain (Ghosh et al., 2025).

For providers

Summer travel brings patients back reporting stiff necks after a week of unfamiliar beds. Asking where they slept, and on what, puts the trip into context.

For patients who travel often, the Travel size keeps the same measured height on the road.

A fitted pillow extends the work of the visit into the hours between visits, alongside the exercise, manual therapy, and other care the provider is already delivering.

Common questions

Why is the first night in a hotel harder?

Research on the first-night effect suggests the brain stays partly alert in a new place. On a first night in an unfamiliar setting, one half of the brain slept less deeply and responded more to unexpected sounds (Tamaki et al., 2016).

Does the first-night effect go away?

In the lab studies, yes. The uneven deep sleep seen on the first night was gone in later sessions (Tamaki et al., 2016), and a follow-up study of 24 adults replicated the first-night pattern (Tamaki & Sasaki, 2019).

Is there a Pillowise pillow for travel?

Yes. The Travel size is measured the same way as the Standard and Queen, in a smaller format to take with you on nights away from home. It is fitted and dispensed through a licensed provider like the others.

Is a contoured pillow from a store enough?

Not reliably. A standard contoured pillow, not fitted to the individual, performed no better than ordinary shapes in a randomized study of 106 side sleepers (Gordon et al., 2009), and no single optimal height can be specified because it depends on four variables that differ from person to person (Lei et al., 2021). A contour helps only if its height matches the person using it. That is what the fitting settles, in a provider's office.

Find a Pillowise provider or become one

Pillowise pillows are clinically measured and dispensed exclusively through licensed healthcare providers as part of broader sleep, posture, and recovery education.

To locate a Pillowise provider near you, visit: Find a Reseller

Licensed healthcare providers interested in offering Pillowise may register here: Become a Reseller

References

Ghosh, S. K., Goyal, M., & Goyal, K. S. (2025). Effect of pillow on pain, disability and sleep quality in patients with chronic neck pain: A systematic review. Rehabilitación, 59(3), 100922. https://doi.org/10.1016/j.rh.2025.100922

Gordon, S. J., Grimmer-Somers, K., & Trott, P. (2009). Pillow use: The behaviour of cervical pain, sleep quality and pillow comfort in side sleepers. Manual Therapy, 14(6), 671-678. https://doi.org/10.1016/j.math.2009.02.006

Jiao, R., Xiao, W., Wang, M., Yu, S., & Li, H. (2025). The impact of pillow height on neck muscle activity: A pilot study. Sleep and Breathing, 29(1), 40. https://doi.org/10.1007/s11325-024-03219-6

Kim, H. C., Jun, H. S., Kim, J. H., Ahn, J. H., Chang, I. B., Song, J. H., & Oh, J. K. (2015). The effect of different pillow heights on the parameters of cervicothoracic spine segments. Korean Journal of Spine, 12(3), 135-138. https://doi.org/10.14245/kjs.2015.12.3.135

Lei, J.-X., Yang, P.-F., Yang, A.-L., Gong, Y.-F., Shang, P., & Yuan, X.-C. (2021). Ergonomic consideration in pillow height determinants and evaluation. Healthcare, 9(10), 1333. https://doi.org/10.3390/healthcare9101333

Radwan, A., Ashton, N., Gates, T., Kilmer, A., & VanFleet, M. (2021). Effect of different pillow designs on promoting sleep comfort, quality, & spinal alignment: A systematic review. European Journal of Integrative Medicine, 42, 101269. https://doi.org/10.1016/j.eujim.2020.101269

Ren, S., Wong, D. W.-C., Yang, H., Zhou, Y., Lin, J., & Zhang, M. (2016). Effect of pillow height on the biomechanics of the head-neck complex: Investigation of the cranio-cervical pressure and cervical spine alignment. PeerJ, 4, e2397. https://doi.org/10.7717/peerj.2397

Tamaki, M., Bang, J. W., Watanabe, T., & Sasaki, Y. (2016). Night watch in one brain hemisphere during sleep associated with the first-night effect in humans. Current Biology, 26(9), 1190-1194. https://doi.org/10.1016/j.cub.2016.02.063

Tamaki, M., & Sasaki, Y. (2019). Surveillance during REM sleep for the first-night effect. Frontiers in Neuroscience, 13, 1161. https://doi.org/10.3389/fnins.2019.01161

Tian, S., Yao, C., Wang, Y., Cao, X., Sun, Y., Wang, L., & Fan, Y. (2025). The individualized optimal pillow height and neck support design for side sleepers. Medical and Biological Engineering and Computing, 63(2), 535-544. https://doi.org/10.1007/s11517-024-03204-x