Randomised controlled trialindependent cross-checkabstract checked★ key study I-LIFE-108 in-depth review
What chronic short sleep does
The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation.
Overview
Van Dongen HP et al.. Sleep 2003 · PMID 12683469 · DOI 10.1093/sleep/26.2.117
Sleeping 6 hours or less for two weeks impaired thinking as much as up to two nights without sleep, and people did not notice.
Does the study support the specific claim? No · Methodological quality: high
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Measure costs of chronic sleep restriction.
- How was the study done?
48 adults randomised to 4, 6 or 8 h in bed for 14 days, or 3 days no sleep.
- How many people, animals or samples were studied?
48 healthy adults.
- What was actually found?
Dose-dependent cognitive deficits.
- How large was the observed effect?
6 h x 14 days ~ up to 2 nights total deprivation.
- What do the results mean in everyday life?
Regularly cutting sleep impairs you even if you feel fine.
- What are the study's limitations?
Short-term, lab-based.
- What does it say about Elawady's specific claim?
Contradicts the claim.
- Do the results apply to Germany and Europe?
Applies; same physiology.
- What can explicitly not be concluded from this study?
Long-term disease outcomes.
Scientific in-depth review
1. Full reference
- Authors
- Van Dongen HP et al.
- Journal
- Sleep
- Year
- 2003
- Identifier
- PMID 12683469 DOI 10.1093/sleep/26.2.117
- Verification
- verified – PubMed efetch 2026-10-26; Crossref update-to/updated-by check
- Retracted
- no
- Corrections
ErratumIn Sleep 2004;27(4):600 (PubMed).
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
Can sleep be chronically reduced without consequences?
3. Study design and population
- Study design
- Randomised controlled trial – Randomised laboratory dose-response experiment
- Population
Healthy adults aged 21-38
- Country
USA
- Period
not stated in abstract
- Sample size
48
- Inclusion and exclusion criteria
not stated in abstract
4. Methods and endpoints
- Exposure / intervention
4 h or 6 h time in bed for 14 days; or 0 h for 3 days
- Comparator
8 h time in bed
- Endpoints
Cognitive performance (PVT lapses etc.), sleepiness, polysomnography
- Statistical methods
Dose-response modelling
5. Actual results
- Results
4 h or 6 h per night for 14 days caused significant cumulative dose-dependent deficits on all cognitive tasks; restriction to 6 h or less produced deficits equivalent to up to 2 nights of total sleep deprivation; subjective sleepiness rose only slightly, so subjects were largely unaware of deficits; lapses related to cumulative wakefulness beyond 15.84 h.
- Absolute risks
not reported
- Authors' conclusion
Even moderate chronic sleep restriction can seriously impair waking neurobehavioural functions in healthy adults.
6. Strengths
- Randomised, controlled laboratory conditions
- Dose-response
7. Weaknesses
- Small; cognitive outcomes only; 14 days
8. Risk of bias
- Orienting tool
- RoB 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- low
- Rationale
Controlled laboratory randomisation.
9. Assessment of the statistical interpretation
Clear dose-response; subjective sleepiness misleads.
10. Relevance to the specific claim
Experimental evidence that habitually short sleep harms functioning, and that people do not notice it - directly against 'staying up late is not harmful'.
11. Independent contrary findings
12. Transferability to Germany and Europe
Universal biology; applies in Europe and Egypt.
13. Overall methodological judgement
Strong experimental contradiction of the harmlessness claim (for short sleep).
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | high |
| Risk of bias | low |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
15. Linked fact checks
- Staying up late is not harmful and eight hours of sleep are not needed; those who say staying up late is harmful 'have not understood the philosophy of the Creator'. – Studies contradicting or limiting the claim