Sleep at every stage of life: how much we need and why it changes

We don't sleep the same way at 5 years old as we do at 45, nor at 45 as we do at 75. Sleep architecture changes throughout our entire life, and understanding those changes is fundamental to avoid confusing normal variations with health problems. It also helps us make better decisions about our habits and rest environment at every stage.

Early childhood: sleep as a developmental tool

Newborns sleep between 14 and 17 hours a day, but in very short cycles of 2 to 4 hours, without distinction between day and night. This is because their circadian rhythm is not yet established.

As they grow, sleep is progressively consolidated. By 6 months, many babies are already sleeping in 6 to 8-hour blocks. By age 2, the need is around 11-14 hours, including naps.

Deep sleep at this stage is critical: most growth hormone is released during slow-wave phases. "Growing while sleeping" is not just a saying.

School-aged children and adolescents

Between ages 6 and 12, children need between 9 and 11 hours of sleep. Deep sleep remains predominant and fulfills crucial functions in memory consolidation and learning.

Something striking happens in adolescence: the biological clock shifts forward. It's not that teenagers don't want to go to sleep early; it's that biologically their bodies start producing melatonin later. They need between 8 and 10 hours, but their natural window for falling asleep can begin at midnight.

This mismatch between school schedules and the adolescent circadian rhythm is one of the reasons why many young people arrive in the classroom sleepy, with consequences for academic performance and mood.

Adults: quality over quantity

The general recommendation for adults aged 18 to 64 is 7 to 9 hours. However, the proportion of deep sleep (phases 3-4) begins to decrease from about age 30.

This means that even if you sleep the same number of hours as you did at 20, you may feel that your rest is less restorative. It's not your imagination: sleep architecture changes.

At this stage, the regularity of schedules, stress management, and the physical sleep environment become especially important. An inadequate mattress, which you could previously compensate for with more hours of deep sleep, starts to be felt more.

Older adults: myths and realities

It is a myth that older adults need less sleep. The need remains at 7-8 hours. What changes is the ability to achieve it: sleep becomes lighter, with more nocturnal awakenings and a greater tendency to shift the sleep schedule earlier.

The causes are multiple: hormonal changes, increased sensitivity to medications, health conditions like sleep apnea or arthritis, and reduced exposure to natural light (which regulates the circadian rhythm).

These sleep interruptions in older adults should not be normalized without consulting a doctor. Chronic fragmented sleep increases the risk of cognitive decline, falls, and cardiovascular disease.

What doesn't change: the importance of a good environment

At all stages of life, the physical sleep environment matters. A mattress that properly supports the spine, an adequate temperature, darkness, and silence are foundations that facilitate rest regardless of age.

What can change is the type of ideal mattress: an active child may tolerate more firmness, an adult with lower back pain needs targeted support, and an older adult may benefit from softer surfaces that reduce pressure on joint points.

Knowing how sleep changes throughout life gives us tools to adapt our habits and environment, and not to resign ourselves to "this is just how it is now that I'm older." There is always room to improve the quality of our nights.