Yes, consistently short sleep may make you more likely to develop a common cold after exposure to a virus. Two controlled rhinovirus studies found that adults who slept for fewer hours before exposure had higher odds of becoming clinically ill than those who slept longer.
That does not mean one late night guarantees you will get sick. It also does not mean sleep can make you immune to infection. The more useful takeaway is that sleep is part of the preparation your body carries into a period of viral exposure, and repeated short nights may matter more than how rested you think you feel.
The two studies used an unusually direct design. Researchers measured participants’ normal sleep before exposing them to rhinovirus under controlled conditions. They then monitored who developed a clinical cold.
A clinical cold was not based only on someone saying they felt unwell. Participants had to show evidence of infection together with objective signs of illness. This matters because tiredness, a headache or a dry throat can feel like the beginning of a cold without confirming that a cold has actually developed.
Across both studies, shorter sleep before exposure was associated with a greater likelihood of becoming ill.[1][2] The studies do not show that every short sleeper will catch a cold, but they do suggest that habitual sleep duration can influence how vulnerable someone is after encountering a virus.
What the first controlled cold study found
In the 2009 study, 153 healthy adults aged 21 to 55 reported their sleep duration and sleep efficiency each morning for 14 consecutive days. Sleep efficiency means the percentage of time in bed that was actually spent asleep.
After this baseline period, participants were quarantined, given nasal drops containing rhinovirus and monitored for five days. Those who averaged less than seven hours of sleep had 2.94 times the odds of developing a clinical cold compared with those who averaged eight hours or more.[1]
Sleep efficiency showed an even larger association. Participants with efficiency below 92 per cent had 5.5 times the odds of developing a cold compared with those whose efficiency was 98 per cent or higher.[1]
The researchers accounted for factors including age, body mass, season, psychological variables, health practices and virus-specific antibody levels before exposure. The associations remained. Interestingly, the percentage of days on which participants said they felt rested was not associated with whether they developed a cold.[1]
That last finding is useful in everyday life. Feeling functional after several short nights does not necessarily mean your sleep has been sufficient. People can become accustomed to tiredness or simply push through it. Your perception of being rested and your recorded sleep pattern are not always the same thing.
Why the second study strengthened the evidence
The first study relied on self-reported sleep. A second study published in 2015 addressed that limitation by measuring sleep with wrist actigraphy, alongside sleep diaries, for seven consecutive days.
The researchers followed 164 healthy adults aged 18 to 55. After sleep monitoring, participants entered quarantine, received rhinovirus nasal drops and were observed for five days using the same general clinical-cold framework.
Compared with participants who slept more than seven hours per night, those sleeping between five and six hours had 4.24 times the odds of developing a cold. Those sleeping for less than five hours had 4.5 times the odds.[2]
Participants sleeping between 6.01 and seven hours did not have a statistically clear increase in risk compared with the group sleeping more than seven hours. Sleep fragmentation was also not associated with cold susceptibility in this study.[2]
Using an objective wrist measurement makes the second study an important follow-up. It reduces the problem of people inaccurately estimating how long they slept. Even so, actigraphy estimates sleep from movement and is not the same as a full laboratory sleep study.
What “four times the odds” actually means
Large figures can sound more certain than they are. The second study reported odds ratios, not a guarantee that someone sleeping five hours will become sick. An odds ratio compares the odds of an outcome between groups. It does not mean that four out of every five short sleepers will catch a cold.
The confidence intervals around the estimates were also wide. That means the exact size of the association is uncertain, even though the overall pattern favoured longer sleep. The safest interpretation is not that five hours creates one precise level of risk. It is that adults with very short sleep were meaningfully more susceptible in these controlled samples.
The sleep categories should not be treated as hard biological cut-offs either. Seven hours is not a magic shield, and a night of six hours does not automatically make someone vulnerable. The studies compared groups based on their average sleep across several nights. They are more relevant to repeated patterns than to an isolated late night.
Sleep duration and sleep efficiency are different
Sleep duration is the total amount of time you are asleep. Sleep efficiency looks at how much of your time in bed is spent sleeping.
For example, someone may spend eight hours in bed but remain awake for long periods before falling asleep or during the night. Their sleep opportunity looks adequate, but their actual sleep duration and efficiency may be lower.
The 2009 study found associations for both shorter sleep and poorer efficiency, with efficiency appearing to account for more of the effect when both measures were considered together.[1] The 2015 study found that objectively measured duration predicted cold susceptibility, while fragmentation did not.[2]
Those results are not identical, which is another reason to avoid reducing sleep health to one tracker score. Duration matters, but the broader pattern includes whether you allow enough time for sleep and whether you can use that opportunity effectively.
Practical ways to protect your sleep before you feel run-down
- Work backwards from your wake time. If you want more than seven hours of actual sleep, allow extra time for settling down and brief periods awake during the night.
- Look at your weekly pattern. One short night is different from repeatedly sleeping five or six hours. Review the pattern rather than judging your health from a single morning.
- Create a realistic evening cut-off. Set a point when work, training and scrolling finish. A bedtime target is less useful if other activities regularly push it back.
- Do not rely only on how rested you feel. The first study found that perceived restfulness did not predict cold development. Consider actual sleep opportunity as well as your morning energy.
- Protect sleep during demanding periods. Travel, heavy workloads, hard training and increased exposure to other people can all compete with sleep. Plan for that pressure before the short nights accumulate.
A wearable can help reveal a trend, but its nightly estimates are not perfect. Use it to notice consistent patterns rather than reacting to every score. If you regularly struggle to fall asleep, wake repeatedly, snore heavily, gasp during sleep or remain unusually tired despite allowing enough time in bed, speak with a qualified health professional.
What these studies cannot prove
Both studies measured sleep before viral exposure, which helps establish that the sleep pattern came before the illness. However, neither study randomly assigned participants to different sleep durations. Other unmeasured differences between shorter and longer sleepers could have contributed to the results.
The participants were healthy adults aged 18 to 55, so the findings may not apply in exactly the same way to children, older adults or people with significant health conditions. Both studies also used rhinovirus under controlled conditions. They do not establish the same risk figures for influenza, COVID-19 or every other infection.
The research examined susceptibility after exposure. It did not test whether extending sleep would prevent a cold, shorten an existing illness or replace other sensible health measures. Sleep should be viewed as one part of your general routine, not as a treatment.
The takeaway
The best available conclusion from these two controlled studies is straightforward. Adults who regularly slept for fewer hours before rhinovirus exposure were more likely to develop a clinical cold than those who slept longer. The strongest pattern appeared among people averaging five to six hours or less.
You cannot control every exposure, and one good night does not guarantee protection. What you can control is whether sleep is repeatedly sacrificed. Giving yourself enough opportunity to sleep, watching the pattern across your week and addressing persistent sleep problems are practical steps that support your wider health routine.
For more practical, evidence-led guidance, explore the ProActive Health Articles.
Sources
- Cohen S, Doyle WJ, Alper CM, Janicki-Deverts D, Turner RB. “Sleep Habits and Susceptibility to the Common Cold.” Archives of Internal Medicine. 2009. View on PubMed.
- Prather AA, Janicki-Deverts D, Hall MH, Cohen S. “Behaviorally Assessed Sleep and Susceptibility to the Common Cold.” Sleep. 2015. View on PubMed.
