Why our brains get so tired in the afternoon

t’s known as the dreaded 2:30 feeling.

You’ve had your eight hours of sleep, a very productive morning and a healthy lunch - but as the afternoon hits you start to fall into a post-lunch slump.

Feeling drowsy after lunch is completely natural, according to Dr Fiona Kerr, a neuro specialist from the University of Adelaide, who explains that humans are “built for two sleeps a day”.

“Sleep deprivation in general has a number of negative consequences to the creative process and to general and mental health,” she explains.

“The primary effect is the blocking of neurogenesis through increases in corticosterone levels but there is also a drop in attention capacity, executive function, working memory, quantification skills, logical reasoning, motor dexterity and mood.”

She adds the slump in the afternoon occurs because our bodies are effectively “programmed to nap” at that time.

“A major reason for this is that human beings are biphasic (physically designed for two sleeps a day), with two major bodily rhythms (homeostatic sleep drive and circadian arousal) which pull us in different directions in terms of staying awake or sleeping, but they fascinatingly align in the middle of the day to create a ‘nap zone’.

Dr Kerr suggests workers would benefit from a 15-minute midday nap, explaining it can offer a multitude of health benefits

They include increases in “cognitive function, memory, alertness, perception levels, stamina, mood, motor skills and creativity - along with decreased stress levels”.

“The most common nap is 15 to 20 minutes (often called the Stage 2 nap) which refreshes the brain and increases alertness and motor performance,” she adds.

“Having a nap of twenty minutes is also more beneficial than sleeping for an extra twenty minutes in the morning.

Research shows that a nap will temporarily improve mental operations, performance, reaction times and subjective feelings of alertness which can last up to 2 - 3 hours, according to Dr Kerr.

Napping at work: Is it really possible to sleep on the job?

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