Why do humans sleep? Most people spend one-third of their lives asleep. For most of human history, individuals have been much more vulnerable to enemies and predators when sleeping. But still, everyone sleeps and cannot help but do it. So, there must be a good reason for sleep, an evolutionary advantage.
One reason for sleeping may be to rest the brain and body. Nevertheless, most organs continue to work during sleep. In particular, the brain is highly active during sleep.1 Sigmund Freud thought one purpose of sleep was to grapple with negative thoughts buried in the unconscious through dreams. Sleep definitely helps to consolidate memories and learning. Some have speculated that during sleep unused synapses are pruned, strengthening the rest of the synapses in the same way that pruning dead branches enhances the health of a rose bush. Together, these all might seem reason enough to sleep.
Identify all potential conflicts of interest that might be relevant to your comment.
Conflicts of interest comprise financial interests, activities, and relationships within the past 3 years including but not limited to employment, affiliation, grants or funding, consultancies, honoraria or payment, speaker's bureaus, stock ownership or options, expert testimony, royalties, donation of medical equipment, or patents planned, pending, or issued.
Err on the side of full disclosure.
If you have no conflicts of interest, check "No potential conflicts of interest" in the box below. The information will be posted with your response.
Not all submitted comments are published. Please see our commenting policy for details.
Komaroff AL. Does Sleep Flush Wastes From the Brain? JAMA. 2021;325(21):2153–2155. doi:10.1001/jama.2021.5631
Coronavirus Resource Center
Customize your JAMA Network experience by selecting one or more topics from the list below.
Create a personal account or sign in to: