#146 - How Sleep Changes Across the Human Lifespan

0:02Matt Walker: Hi there, it's Matt here and welcome back to the podcast. For this episode, I want to travel a single question across the whole of a human life. How does sleep change as we age and why do certain moments make it so much harder? It is the question a parent asks while holding a baby who is wide awake at three in the morning. The question a teenager asks when sleep will not come and the alarm is set for six. It is asked during pregnancy through the heat and disruption of menopause after a bereavement and at the end of a working life. There is no single answer. And I want to say that at the outset.

0:42Matt Walker: Human lives do not unfold as seven identical steps. Not everyone becomes a parent. Not everyone experiences pregnancy or menopause. Grief and trauma can arrive at any age, and retirement can be chosen, imposed, delayed, or never reached at all. So the stages I am about to describe are not deadlines, diagnoses, or destinies. They are patterns seen across groups of people. A population average can tell us what is common. It cannot tell any one person what will happen to them. With that care in place, let us begin where sleep itself begins. A newborn sleep is not a smaller version of adult sleep.

1:23Matt Walker: It is organized differently from the start. Newborns spend a much larger proportion of the night in what researchers call active sleep, the early life counterpart of rapid eye movement or REM sleep. In an adult, REM usually occupies around a fifth to a quarter of the night. In a newborn, active sleep can occupy roughly half. That difference is thought to support the extraordinary development taking place in the infant brain. Though one qualification matters, we cannot know whether a newborn's inner experience resembles the dreams an adult can remember and describe. Active sleep is visible and measurable.

2:05Matt Walker: The content of an infant's mind is not. The timing differs too. Adult sleep cycles average roughly 90 minutes. Infant cycles are shorter, often around 50, and sleep is scattered across the day and night, while the circadian system is still assembling itself over the first 2 or 3 months. This is why early sleep can feel so relentless. But waking is not the same as crying, and a baby who stops signalling has not necessarily stopped waking. Consolidation happens, but not in a straight line. In one large study, only about one in six three-month-olds met the definition of sleeping through the night, and waking remains common well past six months.

2:50Matt Walker: And there is one boundary that no sleep advice may cross. In the United States, the American Academy of Pediatrics recommends placing an infant on their back on a firm, flat, separate sleep surface with no pillows, loose bedding, or soft objects in the caregiver's room for at least the first six months. A sofa or armchair is an especially dangerous place to fall asleep with a baby. Families elsewhere should follow their own public health guidance. Frequent waking is not evidence that you have failed, that your baby is defective, or that you missed some narrow window in which sleep had to be fixed.

3:30Matt Walker: The next great shift arrives with puberty and it is not a matter of attitude or discipline. As puberty progresses, the circadian clock tends to run later and sleep pressure, the drive to sleep that accumulates across the waking day, appears to build differently, allowing many adolescents to stay awake far later than they could as children. Evening light delays the clock at any age and phones add stimulation and displaced bedtime. But a teenager's late sleep is not adequately explained by a glowing screen or a shortage of willpower. The collision comes when a later biological night meets an early social morning.

4:11Matt Walker: Teenagers aged 13 to 18 are generally advised to obtain 8 to 10 hours in each 24, and an adolescent who cannot fall asleep until late but must rise at 6 or 7 may be placed in a schedule that makes that range nearly unreachable. Sleeping much later at the weekend provides some genuine recovery, though a large swing in timing can make Sunday night harder still. Later, school start times have repeatedly been associated with longer sleep and less daytime sleepiness, with the size of the benefit varying between schools and studies. Morning daylight, a reasonably stable wake time, and dimmer light before bed may help.

4:51Matt Walker: but they work best offered as support rather than surveillance. If you live with a teenager who seems unable to wake, begin with curiosity rather than contempt. Ask when sleepiness actually arrives, what the schedule demands, and whether anxiety, depression, medication, substance use, or another sleep disorder may be involved. Severe daytime sleepiness deserves attention, not ridicule.

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7:44Matt Walker: Pregnancy can reshape sleep before the body visibly changes at all. In the first trimester, many people feel an intense sleepiness that is difficult to convey to anyone who has not experienced it. Later, sleep may become lighter and more interrupted by discomfort, reflux, the need to urinate, fetal movement, pain, temperature, anxiety, and changes in breathing. Restless leg syndrome becomes more common, particularly later in gestation. Across large reviews, roughly one in five pregnant people experiences it, though estimates vary. Snoring and sleep-disordered breathing may emerge or worsen, and insomnia symptoms become more frequent as the pregnancy progresses.

8:29Matt Walker: It would be misleading, though, to file all of this under the merely mechanical or to promise it will evaporate the moment the baby arrives. Some contributors do ease, others continue, and physical recovery, hormonal change, feeding, pain, anxiety, depression, and the needs of a newborn introduce entirely new forms of disruption. There is no virtue in suffering silently here. An uncomfortable urge to move the legs, new or loud snoring, gasping, pauses in breathing, severe daytime sleepiness, or persistent insomnia should all be raised with a clinician. These are symptoms worthy of care, not complaints to be endured on the grounds that pregnancy is temporary.

9:15Matt Walker: And to anyone lying awake tonight, your sleep may well change again, but you do not have to pretend the present night is easy or accept that you are somehow managing pregnancy badly because rest has become difficult. After a child is born, caregivers meet a form of tiredness that runs well beyond anything a watch records. In one large German study, first-time mothers reported sleeping about an hour less per night during the first three months after birth than they had before pregnancy. Fathers reported a smaller average reduction of about 20 minutes. Sleep improved after that low point, yet average self-reported duration had still not fully returned to the pre-pregnancy level six years later.

10:01Matt Walker: Those are averages from one population, not a rule for any family, and they do not mean each parent accrues a six-year sleep debt or that all families divide the night the same way. Families include single parents, two mothers, two fathers, adoptive parents, grandparents, and other caregivers, and leave, income, work, health, and culture change the experience profoundly. Total sleep is only part of it. Repeated interruptions are draining in their own right, particularly when they arrive unpredictably and the caregiver stays alert for the next cry, though it is too strong to claim that fragmentation rather than duration does the real damage, or that sleep taken in pieces has little value, both matter.

10:46Matt Walker: So the most useful question is not simply how many hours you got, but who is carrying the night, who is carrying the day, and who is able to stop being responsible for long enough to actually rest. Where it is safe and feasible, families can protect a block of rest for whoever is under greatest strain, but no arrangement should override infant safe sleep guidance or the realities of breastfeeding, and just take shifts is impossible advice for a single parent or a nursing parent without pumping support. Often the missing resource is not technique, but another pair of hands, paid leave, flexible work, meals, child care, someone who can take over while a parent sleeps.

11:28Matt Walker: And if sleeplessness comes with persistent despair, panic, frightening thoughts, or an inability to sleep even when given the chance, seek professional help urgently. Postpartum mental health conditions are medical conditions, not private failures. Sleep changes again through perimenopause and beyond. For many women, hot flushes and night sweats sit at the center of it. In laboratory studies, objectively detected flushes and awakenings frequently occur close together, though the direction is hard to disentangle. A flush may provoke waking, waking may make a flush more noticeable, or both may share an underlying physiology.

12:10Matt Walker: Sleep at this stage is also shaped by mood, pain, caregiving, work, medication, and insomnia that began years earlier. After menopause, the risk of obstructive sleep apnea rises. Sleep apnea does not always resemble the stereotype of a loudly snoring man. Symptoms such as gasping, morning headaches, unrefreshing sleep, fatigue, or stubborn insomnia deserve clinical attention. Menopausal hormone therapy can improve sleep for some women, particularly when vasomotor symptoms are driving the disruption. The evidence is considerably less clear for treating sleep in women without them. It is not a universal sleeping medication, and its benefits and risks depend on the person, the symptoms, the formulation, the route, the timing, and the medical history.

13:01Matt Walker: A conversation for a qualified clinician. For chronic insomnia, Cognitive Behavioral Therapy for Insomnia, or CBTI, remains the well-supported first-line treatment, and it can run alongside care for menopausal symptoms rather than forcing a choice between hormonal and psychological explanations. Human sleep rarely respects such neat divisions. Above all, a woman who says she is exhausted should not have that minimized as an inevitable part of getting older. Common does not mean trivial.

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15:13Matt Walker: There is no scheduled age for the next kind of disruption. It may follow the death of someone loved, an accident, violence, displacement, or illness. Any event that divides a life into before and after. Grief and trauma are not interchangeable. Grief is a human response to loss. Trauma describes exposure and response to overwhelming threat. Some people experience both. Some develop prolonged grief disorder or post-traumatic stress disorder, and many do not. And not developing a disorder does not mean the experience was slight. Sleep tends to suffer either way. A bereaved person may dread the quiet of bedtime, wake reaching for someone no longer there, or feel that sleep is itself a kind of betrayal.

16:00Matt Walker: Someone affected by trauma may face hypervigilance, nightmares, or a body that resists the vulnerability sleep requires. Telling either person to practice better sleep hygiene can feel painfully inadequate. Research does find links running in both directions. More severe sleep disturbance can accompany or predict more persistent distress, and distress further disrupts sleep. But a prediction is not a verdict, and an association does not prove that fragmented REM sleep causes PTSD, or that restoring it will resolve trauma. REM sleep is involved in emotional memory, but phrases like overnight therapy can outrun the evidence and place an unfair burden on the person who cannot sleep.

16:46Matt Walker: Nor is a wrist-worn device the final authority. Consumer trackers infers sleep indirectly and cannot capture dread, nightmares, loneliness, or the meaning of lying awake. CBTI is effective for chronic insomnia, including for many people who also live with PTSD. And early work in bereaved parents suggests it can help there too, though that evidence remains limited. It is not a treatment for grief itself, and better sleep does not bring mourning to an end. If sleep has become a place of fear or you are struggling to function, you deserve help now. You do not have to wait until some arbitrary amount of time has passed, and if you feel at risk of harming yourself, contact emergency or crisis support in your country immediately.

17:36Matt Walker: That is not a failure of resilience. It is an act of protection. Retirement, finally, is sometimes associated with an easing of sleep difficulty. Longitudinal studies have found reductions in self-reported insomnia symptoms around the transition, alongside later timing, somewhat longer sleep, and a smaller gap between work days and free days, plausibly because retirement removes an imposed early start and lets someone sleep closer to their preferred timing. But this work is largely observational. It cannot establish that retirement acts like a treatment, and the average improvement is no promise to any individual.

18:16Matt Walker: Retirement can equally bring illness, bereavement, caregiving, financial fear, isolation, or an unwanted departure from work, and those who retire because of poor health often sleep worse. Time away from work is not a sleeping pill. That metaphor turns a social privilege into a prescription. The more defensible lesson is that schedules and working conditions shape sleep and greater control over one's time may help, an insight that should inform workplaces as much as retirements, nor is it accurate to say sleep does not change with age. Healthy aging commonly brings earlier timing, more awakenings, less deep, slow-wave sleep, and altered circadian and homeostatic regulation.

19:02Matt Walker: Those shifts are real, but they do not mean severe insomnia should be shrugged off as normal, or that older adults cannot be helped by CBTI, and that is what connects all seven of these stages. Not the promise that sleep returns to some earlier normal, sometimes it does, sometimes it settles into a different pattern, and sometimes the life event passes while the insomnia stays and deserves treatment. Sometimes the greatest obstacle is not inside the sleeper at all, but in a school timetable, a working condition, an unequal caregiving load, unsafe housing, illness, or isolation. A difficult night is not a moral test.

19:41Matt Walker: A person is not weak because sleep will not come, and a family is not failing because a baby wakes. The aim is not perfect sleep through a perfectly ordered life. It is to understand what this particular person in this particular season is carrying and then to offer care that is accurate, safe, and kind. That is where I will leave it for today. I hope you found that not just interesting but useful too in the event you are facing any of these challenges right now. Let me know if the solutions described were useful or not. I'm always keen to learn what is making a difference. And until next time, please take good care, sleep a sound sleep, and bye for now.

20:25Thank you.