For an effective summer nap without feeling groggy (sleep inertia), it is recommended to limit the duration, ideally between 10 and 20 minutes.

noli's read

This advice is solidly supported by public health recommendations and sleep research. Sleep inertia, that state of confusion upon waking, occurs primarily when one wakes up after a deep sleep phase. Evidence shows that a short nap (10-20 min) allows one to remain in light sleep stages, offering a boost in alertness without causing this lethargic state. A meta-analysis (Leong et al., 2022) confirms that while longer naps can help in cases of sleep debt, they increase the risk of inertia. Health authorities, such as the Assurance Maladie, also validate the 12 p.m. to 3 p.m. window to minimize the impact on the nocturnal rhythm. There is, therefore, no exaggeration here, but rather an effective popularization of well-documented physiological mechanisms.

the sources

No named source held this one up — that absence is part of the verdict.