Daytime Naps: Why 20 Minutes Helps and 40 Can Make You Feel Worse
Daytime sleep is often treated as something secondary a short pause between tasks, an attempt to “reset.” In reality, it is a tool that can either support the body or quietly undermine well-being. The difference depends on duration and timing.
Thomas Michael Kilkenny, DO, director of the Institute of Sleep Medicine at Northwell Staten Island University Hospital, emphasizes that a short daytime nap can improve daily life, especially if a person does not get enough quality sleep at night. The problem is that sleep deprivation is not just about feeling tired. Research links chronic lack of sleep to impaired cognitive function, elevated blood pressure, diabetes, heart and kidney disease, fatty liver disease, depression, and increased inflammation in the body. It is also associated with weakened immunity and a higher risk of infections.
In other words, the question of napping is not about laziness. It is about compensating for what the body did not receive at night.
At the same time, the mere act of dozing off does not automatically guarantee benefits. A study published in the journal Sleep Health found that a quick daytime nap may correlate with larger brain volume. Since the brain naturally shrinks with age, this finding suggests a potential role in supporting cognitive health. Daytime naps have also been associated with increased creativity and improved mood. But there is a crucial condition.
The ideal length of a nap is no more than 20–30 minutes.
Even shorter naps around 10 minutes can be effective. Within this window, the brain gains restorative benefits without entering deeper sleep stages.
The problem begins after about 30–45 minutes. At that point, the body transitions into deeper stages of non-REM sleep. If a person wakes during this phase, sleep inertia can occur a state in which the body is awake but the brain is not fully alert. It may involve:
- disorientation,
- slowed motor skills,
- impaired coordination,
- difficulty with thinking and communication,
- memory problems,
- irritability,
- low mood.
This explains why people often feel worse after a long nap than before it. The brain intended to complete a deeper sleep cycle but was interrupted.
Timing also matters. Sleep experts identify the optimal window between 1:00 p.m. and 3:00 p.m. During this period, the body naturally experiences a circadian dip in energy levels. This is not weakness or simply the result of lunch it is biology. Napping later in the day increases the risk of disrupting nighttime sleep. Daytime sleep, then, is not a universal recommendation to “lie down whenever you’re tired.” It is a precise tool that requires intentional use.
In a modern rhythm where sleep deprivation has become common, a short nap can partially offset some negative effects. But it does not replace proper nighttime rest. If someone consistently sleeps only four or five hours per night, twenty minutes in the afternoon will not solve the underlying problem. The paradox is that daytime sleep often carries a negative reputation. It is sometimes seen as a sign of weakness or poor discipline. Yet scientific data show that properly timed short naps increase alertness, productivity, and emotional stability.
The difference between benefit and harm lies in duration.
10–20 minutes means restoration.
40–60 minutes risks waking up in cognitive fog.
A nap is not a trend or indulgence. It is physiology. And like any tool, it works only when used deliberately not at random.
About the Author
Related posts:
Sleep or Workout: What’s Actually Better for You and Why the Answer Isn’t That Simple 
What sleep deprivation is and why it destroys more than it seems 
Why Women May Benefit from Sleeping Separately: What Science Says About Sleep and Health 
Can You Live a Nighttime Lifestyle and Stay Healthy? Myths, Science, and the Reality of War-Time Ukraine
