Yahoo News asks a sleep physician about how to nap without disrupting your circadian rhythm.

According to Dr. Sujay Kansagra, the director of the Duke Pediatric Neurology Sleep Medicine Program, the ideal afternoon nap should be 20 to 30 minutes long. “Taking a 20- to 30-minute nap can help combat grogginess and boost mood and energy,” Kansagra told The Active Times in an email. A study published in the journal Clinical Neurophysiology showed that a 20-minute nap, also known as a “power nap,” can boost your mood and productivity for hours afterward.

But if you let your nap stretch on for too long, you can end up doing more harm than good — disrupting your circadian rhythm and waking from your nap feeling even sleepier. “It is important to time your nap appropriately to avoid entering deeper sleep cycles,” Kansagra added. “When your body enters deeper stages of sleep, or even completes a 90-minute sleep cycle in a longer nap, you are likely to feel more tired afterwards rather than refreshed.” The other effects of sleep deprivation may also start to feel more severe.

Get the full story at yahoo.com.