Sleep across a lifetime

Sleep is not a fixed requirement met differently at different ages — the structure of the sleep itself changes across life, and knowing how prevents a good deal of unnecessary alarm.

How much

Consensus recommendations from sleep organisations give ranges rather than numbers, and the ranges are wide.

Newborns require the most by a considerable margin, with the requirement falling steeply through infancy and childhood.

School-age children need substantially more than adults, and adolescents more than is generally provided.

Adults are usually given a range of around seven to nine hours, with individual requirements distributed around that and a small minority genuinely needing less.

Older adults have a similar requirement to younger adults, which contradicts the common belief that older people need less — what changes is the ability to obtain it in one continuous block.

The practical test of adequacy is not the number but whether you wake feeling restored and function without excessive sleepiness on days when nothing is imposed.

Infancy and childhood

Newborns have no circadian rhythm at birth; it develops over the first months, which is why the first weeks are so relentless.

Sleep cycles are shorter in infants, meaning more frequent transitions and more opportunities to wake.

Night waking beyond infancy is normal in a substantial proportion of children and is frequently pathologised.

Slow-wave sleep is at its greatest depth in childhood, which is why children are so difficult to wake and why non-REM parasomnias cluster here.

Adolescence

Where biology and institutions collide.

Puberty is accompanied by a well-documented delay in circadian timing, meaning teenagers genuinely become sleepy later and wake naturally later.

Combined with early school start times, this produces chronic sleep restriction in a large proportion of adolescents, with documented effects on mood, academic performance, risk behaviour and road accidents.

Studies of later school start times have consistently found increased sleep duration and improvements in several of these outcomes, which is one of the more actionable findings in the field.

Which makes the teenager who cannot get up a biological phenomenon rather than a moral one, though phones and evening light exposure compound it considerably.

Adulthood

The most stable period, and the one most affected by circumstance.

The main determinants become work schedules, caring responsibilities, alcohol, stress and, from midlife, the accumulation of conditions that disturb sleep.

Pregnancy disrupts sleep substantially, through physical discomfort, urinary frequency, restless legs, which is markedly more common in pregnancy, and increased apnoea risk.

New parenthood produces fragmentation that persists for months to years, with the load frequently distributed unequally, which is worth negotiating explicitly rather than by default.

Midlife and menopause

A recognised transition point for sleep.

Insomnia prevalence rises around the menopausal transition, driven by vasomotor symptoms, mood changes and hormonal shifts.

Sleep apnoea risk in women rises markedly after menopause, approaching male rates, and it is substantially underdiagnosed because presentations differ.

Which means that a woman in her fifties sleeping badly deserves consideration of both, rather than being handed a sleep hygiene leaflet.

Older age

Where normal change is frequently mistaken for pathology.

Slow-wave sleep declines substantially with age, which means lighter sleep and more awakenings — this is normal ageing rather than a disorder.

Circadian timing advances, so older people become sleepy earlier and wake earlier.

Total sleep becomes more fragmented and more likely to include daytime naps.

What is not normal ageing: excessive daytime sleepiness, which should be investigated; sleep apnoea, whose prevalence rises with age; restless legs, which is associated with iron status and kidney function; and the sleep disruption caused by pain, nocturia, medications and depression.

Sedative prescribing in older adults carries particular risks of falls, fractures and cognitive effects, which is why non-drug treatment is emphasised strongly in this group.

What holds across all ages

Regularity of timing matters more than most single interventions, and evidence from large cohort studies has found sleep regularity to be a strong predictor of outcomes, in some analyses stronger than duration.

Morning light exposure anchors the rhythm at every age.

Physical activity improves sleep across the lifespan.

And the environment — dark, cool, quiet — does not become less important with age, though it is frequently neglected in institutional settings where older adults sleep worst of all.

General information only, not medical advice. Consult a qualified clinician about persistent sleep problems at any age.