Sleep and Immune Function During Cold and Flu Season

Last updated: October 2026

Sleep duration is the variable in this area with the strongest evidence: in a study where 164 adults wore wrist actigraphs for a week and were then quarantined and given rhinovirus nasal drops, those sleeping under five hours were 4.5 times more likely to develop a cold than those sleeping more than seven (Prather et al., 2015). An earlier study using the same design found a similar pattern (Cohen et al., 2009). Cold and flu season is when patients ask what they can change, and hours of sleep is the answer with the strongest evidence behind it.

Key takeaways

In a viral challenge study of 164 adults, those sleeping under five hours were 4.5 times more likely to develop a cold than those sleeping more than seven (Prather et al., 2015).
In 153 adults exposed to a cold virus, those averaging under seven hours of sleep were 2.94 times more likely to develop a clinical cold (Cohen et al., 2009).
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.

How much does sleep actually affect getting sick?

Two studies answer this directly, and both used the same unusually strong design. Participants were tracked at home, then quarantined, then deliberately exposed to a cold virus.

In the earlier study, 153 adults reported sleep duration and sleep efficiency for 14 consecutive days before exposure. Those averaging under seven hours were 2.94 times more likely to develop a clinical cold than those getting eight or more. Those with sleep efficiency below 92 percent, meaning the proportion of time in bed actually spent asleep, were 5.50 times more likely (Cohen et al., 2009).

The later study replaced self-report with wrist actigraphy in 164 adults. Under five hours produced an odds ratio of 4.50, and five to six hours produced 4.24, both compared with more than seven hours, while six to seven hours carried no significant increase. The association held independent of pre-challenge antibody levels, demographics, season, body mass index, and health practices (Prather et al., 2015).

In both studies, participants were given the virus under controlled conditions rather than asked to recall past illness.

What does sleep do to the immune system?

The relationship runs in both directions. Immune activation changes sleep, and sleep changes both the innate and adaptive arms of the immune response (Besedovsky et al., 2019).

Sleep and immune signaling are reciprocal, and disturbed sleep contributes to dysregulated inflammatory and antiviral responses (Irwin, 2019).

The practical version for a patient is short. Sleep is not downtime for the immune system. It is when a substantial part of the work happens.

Where a pillow fits, and where it does not

A pillow does not fight infection, and we make no claim that it does. No study has tested whether a fitted pillow changes infection rates.

The evidence does establish a chain. In a cross-sectional study of 3,593 hospital workers, a high pain score raised the risk ratio for poor sleep to 1.48, so musculoskeletal pain is associated with poor sleep (Vinstrup et al., 2018). Short sleep, in turn, predicts susceptibility to the common cold in viral challenge studies (Cohen et al., 2009; Prather et al., 2015).

A pillow sits at the first link, neck support during sleep, not the last one. No study has measured whether a fitted pillow changes sleep duration. Sleep duration is the variable with the trial evidence.

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).

Pillow height changes cervical alignment measurably. A radiographic study of 16 adults found that as height increased, T1 slope and C2-7 Cobb angle increased while neck tilt decreased (Kim et al., 2015).

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.

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.

Scope

The pillow trial literature is small, with individual studies running from 9 to 106 participants, and the most recent systematic review found no clear advantage for any single pillow type in chronic neck pain (Ghosh et al., 2025). The alignment and muscle-activity findings are consistent and directly measured. We position a fitted pillow as an adjunct to exercise, manual therapy, and other conservative care rather than as a treatment for a condition, and not as an intervention for infection risk.

For providers

Patients ask what they can change in October. Sleep duration is the answer with the strongest evidence, and it is a legitimate clinical question during cold and flu season.

Ask how many hours the patient is actually getting. The actigraphy viral challenge study found the difference between under five hours and over seven was more than fourfold (Prather et al., 2015).
Ask what is interrupting it. Pain that wakes a patient is a sleep problem as well as a pain problem, and it is one you already treat.
Ask about pillow type, height, and sleep position. It is a one-line question covering a third of the patient's day, and it is usually the part of the plan nobody has asked about.

Common questions

Does not sleeping enough make you more likely to catch a cold?

Yes, in studies where participants were deliberately exposed to a cold virus under quarantine. Sleeping under seven hours was associated with 2.94 times the likelihood of developing a clinical cold compared with eight or more, and sleep efficiency below 92 percent with 5.50 times (Cohen et al., 2009). Using wrist actigraphy rather than self-report, under five hours produced an odds ratio of 4.50 (Prather et al., 2015).

Does a cervical pillow help you recover from illness faster?

No study has tested that, and we make no such claim. What is established is that musculoskeletal pain is associated with poor sleep (Vinstrup et al., 2018) and that short sleep predicts cold susceptibility (Prather et al., 2015). A fitted pillow is about neck support during sleep, and it does nothing to the virus.

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

Besedovsky, L., Lange, T., & Haack, M. (2019). The sleep-immune crosstalk in health and disease. Physiological Reviews, 99(3), 1325-1380. https://doi.org/10.1152/physrev.00010.2018

Cohen, S., Doyle, W. J., Alper, C. M., Janicki-Deverts, D., & Turner, R. B. (2009). Sleep habits and susceptibility to the common cold. Archives of Internal Medicine, 169(1), 62-67. https://doi.org/10.1001/archinternmed.2008.505

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

Irwin, M. R. (2019). Sleep and inflammation: Partners in sickness and in health. Nature Reviews Immunology, 19(11), 702-715. https://doi.org/10.1038/s41577-019-0190-z

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

Prather, A. A., Janicki-Deverts, D., Hall, M. H., & Cohen, S. (2015). Behaviorally assessed sleep and susceptibility to the common cold. Sleep, 38(9), 1353-1359. https://doi.org/10.5665/sleep.4968

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

Vinstrup, J., Jakobsen, M. D., Calatayud, J., Jay, K., & Andersen, L. L. (2018). Association of stress and musculoskeletal pain with poor sleep: Cross-sectional study among 3,600 hospital workers. Frontiers in Neurology, 9, 968. https://doi.org/10.3389/fneur.2018.00968