Researchers believe that irregular and long naps could disrupt natural sleep cycles and might indicate underlying health issues such as diabetes, heart disease, and depression
Sleeping more than 30 minutes in the afternoon may increase the risk of early death, according to a new study. Experts from Massachusetts General Hospital in Boston, USA, tracked over 86,000 adults with an average age of 63 for more than 11 years. During the follow-up period, 5,189 participants—about six per cent—died. The study suggests a potential link between extended daytime naps and higher mortality risk.
Researchers believe that irregular and long naps could disrupt natural sleep cycles and might indicate underlying health issues such as diabetes, heart disease, and depression. Participants in the study wore health tracker devices to monitor sleep habits. The data revealed that those who routinely napped for more than half an hour in the afternoon were more likely to suffer from chronic health problems. While short naps may offer cognitive benefits, excessive napping appears to have detrimental effects when not aligned with healthy nighttime sleep.
This research aligns with sleep guidelines from health organisations. Both the UK’s National Health Service (NHS) and the American Academy of Sleep Medicine recommend limiting naps to early afternoon and keeping them brief—ideally under 30 minutes.
The concern is not about napping itself, but about naps that interfere with nighttime sleep quality or signal poor overall health. Experts note that daytime sleepiness can be a sign of sleep disorders or other conditions that affect sleep quality at night.
In contrast to the risks associated with excessive napping, other studies highlight the cognitive benefits of sleep. A recent study led by researchers at Rice University, Houston Methodist’s Center for Neural Systems Restoration, and Weill Cornell Medical College has shed light on how NREM (non-rapid eye movement) sleep boosts brain performance.
Published in Science, the study demonstrated that NREM sleep helps the brain process and store information more effectively. Researchers found that during this sleep phase, low-frequency delta waves promote neuronal synchronisation. This enhanced brain coordination supports better memory and task performance after sleep.
Dr. Natasha Kharas, a neurological surgery resident at Weill Cornell, explained, “After sleep, neuronal activity became more desynchronised, allowing neurons to fire more independently. This shift improved accuracy in information processing.”
Notably, the improved cognitive performance was seen only in test subjects who actually fell asleep. Those who rested quietly without sleeping did not experience the same benefits.
These findings open doors for new brain stimulation therapies to improve memory and cognitive function, even mimicking some effects of sleep. While short naps can enhance brain power, especially when aligned with natural rhythms, excessive daytime sleep may signal underlying issues and increase health risks.
