Research library.
The 13 sources our articles are based on. Each row links to the article with the full citation and a link to the original source.
| Study | What was studied | Key finding | Article |
|---|---|---|---|
| Rosekind et al. 1994, 1995NASA, Journal of Sleep Research | 40-minute planned cockpit rest on long-haul flights | The nap improved alertness and performance, and the benefit lasted until landing | The NASA nap: what the pilot study actually showed |
| Brooks & Lack 2006Sleep | 5-, 10-, 20- and 30-minute daytime naps after a short night | The 10-minute nap was the most effective | How long should a power nap be? |
| Tietzel & Lack 2002Journal of Sleep Research | Naps from 30 seconds to 10 minutes | Under 90 seconds gave no benefit, 10 minutes did | How long should a power nap be? |
| Hilditch et al. 2016Sleep | 10- and 30-minute naps on a simulated night shift | 30 minutes was followed by sleep inertia, 10 minutes by very little | How long should a power nap be? |
| Smith-Coggins et al. 2006Annals of Emergency Medicine | 40-minute nap opportunity at 3 am, 49 physicians and nurses | Fewer attention lapses and less fatigue at the end of the shift | Naps on the night shift: what hospital studies show |
| Dutheil et al. 2020Sleep | Meta-analysis: 18 night shift studies, 494 participants | Napping improved cognitive performance | Naps on the night shift: what hospital studies show |
| Dutheil et al. 2021IJERPH | Meta-analysis: daytime naps in working-age adults | Performance improved, especially alertness, for up to 2 hours | Naps and the brain: focus and brain volume |
| Paz et al. 2023Sleep Health | UK Biobank, Mendelian randomisation | Habitual napping linked to 15.8 cm³ larger brain volume | Naps and the brain: focus and brain volume |
| Faraut et al. 2015J Clin Endocrinol Metab | Napping after 2 hours of night sleep | No norepinephrine spike, IL-6 stayed normal | Naps, stress and the heart: the benefits and the limits |
| Häusler et al. 2019Heart | 3,462 adults, 5-year follow-up | 1–2 naps a week: 48% lower cardiovascular risk | Naps, stress and the heart: the benefits and the limits |
| Yamada et al. 2015Sleep | Meta-analysis on nap length and health | Daily naps of 60 min or more linked to higher risk | Naps, stress and the heart: the benefits and the limits |
| Hafner et al. 2016RAND Europe | Economic impact of insufficient sleep in 5 countries | The US loses up to $411 bn and 1.23 million working days a year | The cost of fatigue: what lack of sleep costs |
| Waterhouse et al. 2007Journal of Sports Sciences | 30-minute post-lunch nap after a short night | Alertness, memory and sprint times improved | Naps and athletic performance |
Observational studies show associations, not causation. This content does not replace medical advice. If you need a long daytime sleep every day, talk to your doctor.