Getting 7 to 8 hours of sleep each night — don’t settle for just 6 hours
Original: eternity4719 · source details
Original author: eternity4719 · Chinese source: · English adaptation: parveen0029. Translation and grade notes ↗
Bibliographic titles are retained in their original language.
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Cost and benefit at a glance
- Check the cost Cost ↓
- No cost at all. You simply need to set aside 1–2 extra hours each day for sleep. Going to bed earlier requires a bit of willpower.
- Then the source benefit Benefit ↓
- In a randomized controlled trial, 48 healthy adults aged 21–38 were asked to get just 6 hours of sleep per night for 14 consecutive days. Their cognitive performance steadily decli…
In plain terms
After two full weeks of getting only 6 hours of sleep each night, brain performance drops to a level equivalent to going two full nights without any sleep at all. The tricky part is that people don’t notice this effect themselves. Their self-rated sleepiness only rises during the first few days and then plateaus — people sleeping 6 hours report the same level of fatigue as those sleeping just 4 hours. In other words, the belief that “6 hours of sleep is enough for me” is actually a symptom of chronic sleep deprivation.
This guide's cartoon · show illustration
Enlarge illustrationOriginal illustration with Chinese lettering; the English dialogue is below. Humour is a reading aid, not evidence.
English dialogue
- Just five minutes of rest.
- One more notification!
Cost: what it takes
No cost at all. You simply need to set aside 1–2 extra hours each day for sleep. Going to bed earlier requires a bit of willpower.
Benefit: what the source reports
In a randomized controlled trial, 48 healthy adults aged 21–38 were asked to get just 6 hours of sleep per night for 14 consecutive days. Their cognitive performance steadily declined, eventually reaching levels comparable to those seen after two full nights of total sleep loss. Meanwhile, their self-reported sleepiness only increased at first and then remained largely unchanged. There was no difference in self-rated fatigue between the 6-hour and 4-hour sleep groups. Additionally, a meta-analysis of 70 studies found that acute sleep deprivation (lasting no more than 48 hours) leads to a moderate drop in simple attention (effect size g = -0.776) and a much smaller decline in reasoning accuracy (g = -0.125).
Conditions, limits and disagreements
The most important takeaway is that “not feeling sleepy” is not proof that you’ve gotten enough sleep. People who regularly sleep just 6 hours simply get used to the state, but their actual performance does not improve. The results from the meta-analysis apply to staying awake for an entire night; there is only one randomized controlled trial supporting the idea that consistently getting less than 6 hours of sleep has any real negative impact.
Original references
Original bibliographic titles and links are preserved; some titles are in Chinese.
Van Dongen, Maislin, Mullington & Dinges (2003). The cumulative cost of additional wakefulness. Sleep. https://doi.org/10.1093/sleep/26.2.117；Lim & Dinges (2010). A meta-analysis of the impact of short-term sleep deprivation on cognitive variables. Psychological Bulletin. https://doi.org/10.1037/a0018883
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