From: hubermanlab
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Sleep needs vary significantly across the human lifespan. These changes encompass both the amount of sleep required and the structure of sleep, such as the transition between different sleep phases. Understanding these variations can offer insights into optimizing sleep for different stages of life. This article explores the changes in sleep needs from infancy through adulthood and into old age, as discussed by Dr. Matthew Walker on the Huberman Lab Podcast.
Infancy and Early Childhood
In infancy, sleep is polyphasic, meaning it occurs in multiple phases throughout the 24-hour period. Newborns typically go through cycles of wake-sleep every 2 hours. This frequent sleep is necessary for both feeding and because the suprachiasmatic nucleus (the central circadian clock) is not yet fully developed, making the infant unresponsive to light and dark cycles circadian rhythms [00:08:30].
As infants age, around one year, they begin to consolidate their sleep more towards the nighttime, though their sleep remains polyphasic to some extent [00:09:52]. By two or three years old, children generally settle into a biphasic sleep pattern, characterized by a long nighttime sleep and a daytime nap. This daytime nap is biologically advantageous as it can aid emotional regulation and cognitive development cognitive development [00:10:07].
Childhood to Adolescence
By the time children reach the age of five or six, they typically transition to a monophasic sleep pattern, which means they mostly sleep in one long bout throughout the night. This pattern generally continues throughout childhood and into adolescence [00:10:47].
During the teenage years, there is a biological inclination to shift sleep patterns to a later bedtime and later wake time. This change is driven by puberty and the associated hormonal changes hormonal changes, compelling teenagers to prefer sleeping later in the morning, which often conflicts with early school start times [01:23:01].
Adulthood
For most adults, the monophasic sleep pattern persists. The total amount of sleep required generally stabilizes around 7 to 9 hours per night, although individual needs can vary. Some adults may adopt a biphasic sleep pattern, including a siesta-like nap in the afternoon, which appears to be biologically ingrained given the natural postprandial drop in alertness napping [00:26:03].
Old Age
As individuals age further, particularly past the age of 65, a significant decline in the quality and quantity of sleep is observed. This includes a reduction in slow-wave deep sleep and a higher incidence of sleep fragmentation, resulting in lighter and more disrupted sleep [01:25:34].
These changes often lead older adults to nap more frequently during the day. However, there is evidence to suggest that while daytime napping might compensate for poor nighttime sleep, it could potentially predict worse health outcomes if it reflects an underlying issue with sleep quality at night [01:24:13].
Key Takeaways
- Infants need multiple sleep phases throughout the day to support feeding and undeveloped circadian rhythms.
- Children to Adolescents generally transition from polyphasic to monophasic sleep, with a natural preference for later sleep during adolescence.
- Adults often maintain a monophasic sleep pattern but may incorporate naps.
- Older Adults experience reduced sleep quality and quantity, often leading to increased daytime napping, which might correlate with health risks.
Understanding these natural shifts in sleep patterns can aid in adjusting lifestyle and environmental factors to improve sleep quality across different life stages.