You’re in the middle of the afternoon, eyelids heavy, focus slipping. You close your eyes for half an hour and wake up feeling recharged. But later that night, you’re tossing and turning in bed, wondering why you can’t drift off. That midday snooze which felt so refreshing at the time might be the reason.

Naps have long been praised as a tool for boosting alertness, enhancing mood, strengthening memory, and improving productivity. Yet for some, they can sabotage nighttime sleep.

Napping is a double-edged sword. Done right, it’s a powerful way to recharge the brain, improve concentration, and support mental and physical health. Done wrong, it can leave you groggy, disoriented, and struggling to fall asleep later. The key lies in understanding how the body regulates sleep and wakefulness.

Most people experience a natural dip in alertness in the early afternoon, typically between 1pm and 4pm. This isn’t just due to a heavy lunch – our internal body clock, or circadian rhythm, creates cycles of wakefulness and tiredness throughout the day. The early afternoon lull is part of this rhythm, which is why so many people feel drowsy at that time.

Studies suggest that a short nap during this period – ideally followed by bright light exposure – can help counteract fatigue, boost alertness, and improve cognitive function without interfering with nighttime sleep. These “power naps” allow the brain to rest without slipping into deep sleep, making it easier to wake up feeling refreshed.

But there’s a catch: napping too long may result in waking up feeling worse than before. This is due to “sleep inertia” – the grogginess and disorientation that comes from waking up during deeper sleep stages.

Once a nap extends beyond 30 minutes, the brain transitions into slow-wave sleep, making it much harder to wake up. Studies show that waking from deep sleep can leave people feeling sluggish for up to an hour. This can have serious implications if they then try to perform safety-critical tasks, make important decisions or operate machinery, for example. And if a nap is taken too late in the day, it can eat away from the “sleep pressure build-up” – the body’s natural drive for sleep – making it harder to fall asleep at night.

When napping is essential

For some, napping is essential. Shift workers often struggle with fragmented sleep due to irregular schedules, and a well-timed nap before a night shift can boost alertness and reduce the risk of errors and accidents. Similarly, people who regularly struggle to get enough sleep at night – whether due to work, parenting or other demands – may benefit from naps to bank extra hours of sleep that compensate for their sleep loss.

Nonetheless, relying on naps instead of improving nighttime sleep is a short-term fix rather than a sustainable solution. People with chronic insomnia are often advised to avoid naps entirely, as daytime sleep can weaken their drive to sleep at night.

Certain groups use strategic napping as a performance-enhancing tool. Athletes incorporate napping into their training schedules to speed up muscle recovery and improve sports-related parameters such as reaction times and endurance. Research also suggests that people in high-focus jobs, such as healthcare workers and flight crews, benefit from brief planned naps to maintain concentration and reduce fatigue-related mistakes. Nasa has found that a 26-minute nap can improve performance of long-haul flight operational staff by 34 per cent, and alertness by 54 per cent.

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How to nap well

To nap effectively, timing and environment matter. Keeping naps between ten and 20 minutes prevents grogginess. The ideal time is before 2pm – napping too late can push back the body’s natural sleep schedule.

The best naps happen in a cool, dark and quiet environment, similar to nighttime sleep conditions. Eye masks and noise-cancelling headphones can help, particularly for those who nap in bright or noisy settings.

Despite the benefits, napping isn’t for everyone. Age, lifestyle and underlying sleep patterns all influence whether naps help or hinder. A good nap is all about strategy – knowing when, how, and if one should nap at all.

For some it’s a life hack, improving focus and energy. For others, it’s a slippery slope into sleep disruption. The key is to experiment and observe how naps affect your overall sleep quality.

Done wisely, naps can be a valuable tool. Done poorly, they might be the reason you’re staring at the ceiling at midnight.

Talar Moukhtarian is an Assistant Professor in Mental Health at Warwick Medical School, University of Warwick

This article was originally published by The Conversation and is republished under a Creative Commons licence. Read the original article