What Causes Lack of Sleep? The Medical, Hormonal and Lifestyle Reasons, Sorted

Scroll through any short-video feed this month and you will meet a new rule for sleeping better every thirty seconds: tape your mouth shut, drink a magnesium “sleepy girl mocktail,” wear amber glasses from sunset, never let a phone cross the bedroom door. As of September 2026, the hashtag loosely known as “sleepmaxxing” has sent searches for what causes lack of sleep to a multi-year high, and the question underneath the trend is a serious one. Roughly one adult in three in the United States reports regularly sleeping less than the seven hours public-health agencies recommend.

The viral advice is not all wrong. It is just aimed at the wrong target for most people. A tired person does not have a tape problem or a mineral problem; they have a cause, often several, and the causes are surprisingly sortable. Some live in the body, some in the mind, some in hormones that rise and fall on a 24-hour clock, and a great many in the ordinary architecture of a day.

This piece sorts them, grades the evidence behind each, and is honest about where science still shrugs.

What causes lack of sleep? The three-part model sleep clinics actually use

Ask a sleep physician what causes lack of sleep and you rarely get a single culprit. You get a framework. Most clinics use some version of the “three Ps”: predisposing factors, precipitating events and perpetuating habits. It sounds academic, but it explains why one person shrugs off a stressful week while another is still awake at 3 a.m. two years later.

Predisposing factors are the background. They include a family history of insomnia, a naturally “wired” nervous system that runs on high alert, being female (insomnia is reported more often by women, partly for hormonal reasons covered below), and getting older, when sleep becomes lighter and more easily broken. None of these guarantees poor sleep. They lower the threshold.

Precipitating events are the triggers: a bereavement, a new baby, a job loss, surgery, a bout of pain, a new medicine, a move to shift work. Almost everyone sleeps badly after a trigger like this. Insomnia, the clinical term for trouble falling or staying asleep at least three nights a week for three months or more, is diagnosed only when the problem outlives the event that started it.

Perpetuating habits are what keep it going once the trigger has passed. Lying in bed for ten hours hoping to catch sleep. Napping at 5 p.m. Checking the clock. Worrying about tomorrow’s tiredness. Each one is a reasonable response to exhaustion, and each one teaches the brain that bed is a place of effort rather than rest.

This matters because the trending fixes almost all aim at the first two Ps, which are hard to change, and ignore the third, which responds to treatment better than almost anything else in medicine. Keep the model in mind as we go through the causes; it will tell you which ones you can realistically act on.

What changed recently: why sleep moved to the front of the health agenda

Three developments explain why a question as old as the pillow is trending again.

First, sleep was formally promoted to a vital sign for the heart. In June 2022 the American Heart Association rewrote its cardiovascular health checklist, previously “Life’s Simple 7,” into “Life’s Essential 8,” adding sleep duration alongside blood pressure, cholesterol, blood sugar, diet, activity, weight and nicotine exposure. The association set the healthy adult target at 7 to 9 hours a night, citing observational studies linking both short and very long sleep with higher rates of heart disease and stroke. Once cardiologists started asking about sleep in routine visits, patients started searching.

Second, public-health reporting became blunter. The Centers for Disease Control and Prevention now states plainly that about one in three U.S. adults does not get enough sleep and lists insufficient sleep as a risk factor for type 2 diabetes, obesity, depression and motor-vehicle crashes. That framing, sleep loss as a population-level health problem rather than a personal failing, has shaped how newer guidance from the National Heart, Lung, and Blood Institute and major clinics describes the causes.

Third, the medicine cabinet changed. A newer class of prescription sleep medicines, the orexin receptor antagonists (orexin is a brain chemical that promotes wakefulness; these medicines dampen its signal rather than sedating the whole brain), gained regulatory approval in the United States in stages between 2014 and 2022. Their arrival renewed interest in why people cannot sleep, because they work differently from older sedatives. Whether any medicine is appropriate, and which one, is a decision for a prescribing clinician after other causes have been looked for.

Against that backdrop, the viral content did what viral content does: it took a real public-health shift and turned it into products and rituals. The rest of this article is about the underlying causes those rituals skip over.

Medical conditions that quietly steal sleep

A surprising share of “insomnia” is a body complaint wearing a sleep disguise. Clinicians look for these before anything else, because treating the condition often fixes the nights without any sleep-specific therapy.

Pain leads the list. Arthritis, low back pain, fibromyalgia and migraine all fragment sleep, and the relationship runs both ways: a short night lowers the pain threshold the next day, which disturbs the following night. Mayo Clinic and the NHS both name chronic pain among the most common medical contributors to insomnia.

Gastroesophageal reflux disease, or GERD, meaning stomach acid washing back into the food pipe, tends to flare when you lie flat. Night-time heartburn, a sour taste or a dry cough on waking are clues, and late or large evening meals make it worse.

Nocturia, the medical word for waking to urinate, is often blamed on age or fluids but can reflect an enlarged prostate, an overactive bladder, poorly controlled diabetes, or heart failure causing fluid shifts when you lie down. Two or more bathroom trips a night deserve a conversation with a doctor rather than a smaller water glass.

Breathing and heart conditions matter too. Asthma commonly worsens between 2 and 4 a.m. Heart failure can cause breathlessness on lying flat. Chronic lung disease drops blood oxygen during sleep.

Then there is the thyroid. An overactive thyroid gland speeds up metabolism, raises heart rate and produces a restless, hot, can’t-settle feeling at night. An underactive one causes exhaustion that no amount of sleep relieves. Both are picked up with a simple blood test.

Neurological conditions, including Parkinson’s disease and dementia, disturb the brain regions that regulate sleep itself. Allergies and chronic nasal congestion block the airway. Even itchy skin conditions such as eczema reliably wake people in the early hours.

The practical point: if your sleeplessness came with a new physical symptom, start with the symptom.

Sleep disorders in disguise: apnea, restless legs and a misaligned body clock

Some causes of lack of sleep are sleep disorders in their own right, and they are frequently missed because the person does not know they are happening.

Obstructive sleep apnea is the big one. It means the upper airway repeatedly narrows or closes during sleep, so breathing pauses for ten seconds or more, oxygen dips, and the brain briefly rouses to reopen the throat. Those arousals can happen dozens of times an hour without any memory of waking. The person reports “I sleep eight hours and feel like I slept three,” plus loud snoring, gasping, morning headaches, a dry mouth, and dozing off in meetings. Risk rises with higher body weight, a thick neck, a small jaw, being male, and age, but slim people and children get it too. Untreated apnea is linked in large observational studies to high blood pressure, atrial fibrillation and stroke, and it is diagnosed with an overnight sleep study, sometimes at home.

Restless legs syndrome is a neurological condition: an unpleasant crawling, pulling or buzzing sensation deep in the legs, worst in the evening and at rest, relieved temporarily by moving. It makes falling asleep miserable and is often accompanied by periodic limb movements during sleep that the bed partner notices first. Low iron stores, pregnancy, kidney disease and certain medicines (including some antihistamines and antidepressants) can trigger or worsen it, which is why a doctor will usually check a ferritin level.

Circadian rhythm disorders are mismatches between your internal 24-hour clock and the schedule life demands. Delayed sleep phase, common in teenagers and young adults, means the body genuinely is not ready for sleep until 2 a.m. and not ready to wake until 10. Advanced sleep phase, more common with age, does the opposite. Shift work disorder and jet lag are the externally imposed versions. The sleep is often normal; the timing is not.

Each of these has a specific treatment pathway, and none is addressed by lavender spray.

Why can't I sleep when my mind won't switch off? Stress, anxiety and hyperarousal

The single most common answer to “why can’t I sleep?” is not a disease at all. It is a nervous system that has not received the message that the day is over.

Sleep researchers call this hyperarousal: a state in which the brain and body run at higher-than-normal alert levels around the clock, not just at bedtime. People with chronic insomnia show faster brain-wave patterns during sleep, higher night-time heart rates, higher core body temperature, and more of the stress hormone cortisol in the evening, when it should be at its lowest. In practical terms, they are physiologically a little too awake, 24 hours a day, which is why they often feel tired but wired rather than sleepy.

Acute stress is the usual entry point. A deadline, an argument, a frightening diagnosis in the family. The brain treats a threat as a reason to stay vigilant, and vigilance and sleep are mutually exclusive. For most people this resolves in days. For some, the bed itself becomes associated with frustration, and the brain begins to switch on alert mode as soon as the head hits the pillow. That learned association, not the original stress, is what perpetuates it.

Anxiety disorders and insomnia overlap heavily; worry at night is a classic feature of generalised anxiety. Depression is more complicated. It can cause early-morning waking, typically between 3 and 5 a.m. with an inability to get back to sleep, but it can also cause oversleeping. Post-traumatic stress disorder brings nightmares and a startle response that makes deep sleep feel unsafe.

Two things are worth knowing. One: insomnia is not merely a symptom of these conditions; longitudinal studies suggest persistent insomnia raises the risk of developing depression later, so it is worth treating in its own right. Two: the treatment with the strongest evidence for this pattern is a structured behavioural therapy, not a sedative, and we come to it below.

Hormonal reasons for lack of sleep: cortisol, melatonin, menopause and pregnancy

Hormones are chemical messengers released by glands, and several of them are timekeepers. When their rhythm is disturbed, sleep follows.

Melatonin is the hormone the brain’s pineal gland releases as light fades; it signals “night” to the rest of the body and lowers core temperature. Bright light in the evening, especially the short-wavelength light from screens and overhead LEDs, suppresses it. Melatonin does not knock you out the way a sedative does; it opens the gate. Suppress it and the gate opens later.

Cortisol is the opposite messenger. It peaks within an hour of waking to mobilise energy and should drift to its lowest point around midnight. Chronic stress, depression, poorly controlled diabetes and certain medical conditions flatten or invert that curve, leaving cortisol too high when you want to sleep.

Menopause is the most common hormonal cause of new insomnia in women in their late 40s and 50s. Falling estrogen destabilises the body’s thermostat, producing hot flashes and night sweats that wake people repeatedly; estrogen and progesterone also directly influence sleep-regulating brain regions. The NHS and Mayo Clinic both list sleep disturbance among the core symptoms of the menopause transition. Whether hormone therapy is appropriate for a given woman depends on her age, history and risk profile, and that is a decision for her clinician; the evidence that it improves sleep when night sweats are the driver comes from randomised trials and is reasonably strong for that specific situation.

Pregnancy disturbs sleep in every trimester for different reasons: nausea and frequent urination early on, then heartburn, backache, restless legs and a growing belly that makes every position wrong. Premenstrual days bring poorer sleep for many women as progesterone drops.

Thyroid hormones, growth hormone and testosterone all interact with sleep as well; low testosterone in men is associated with lighter, more fragmented sleep, and sleep apnea lowers testosterone, a loop that illustrates how often cause and effect blur in this field.

Medicines, caffeine, alcohol and nicotine: the chemistry of a bad night

Before blaming your mattress, read the labels in your kitchen and bathroom.

Caffeine blocks adenosine, the brain chemical that builds up across the day and creates sleep pressure. Its half-life, meaning the time for your body to clear half of a given amount, averages around five to six hours in healthy adults and is longer in pregnancy, with some medicines and in people who metabolise it slowly. A coffee at 3 p.m. still has a meaningful presence in the bloodstream at 9. Randomised crossover studies in which volunteers took caffeine or placebo at set times before bed show that even caffeine six hours before bedtime measurably shortens total sleep and reduces deep sleep, often without the person noticing.

Alcohol is the most misunderstood. It is a sedative, so it does speed up falling asleep, which is why the myth persists. Then it is metabolised, the sedation wears off around the middle of the night, and the rebound brings lighter sleep, more awakenings, suppressed REM (the dreaming stage), more snoring because throat muscles relax, and more bathroom trips. Laboratory sleep studies show this pattern consistently.

Nicotine is a stimulant, and smokers also experience mild withdrawal overnight, which can wake them. Vaping delivers the same molecule.

Prescription and over-the-counter medicines are a large and underappreciated category. Classes commonly associated with insomnia or fragmented sleep include some antidepressants, corticosteroids, beta blockers (which can also cause vivid dreams and reduce melatonin), stimulants for attention deficit disorder, decongestants containing pseudoephedrine, some asthma medicines, thyroid hormone if the level is too high, and diuretics taken late in the day. Sedating antihistamines in “PM” products can leave a foggy hangover and lose effect within days.

If you suspect a medicine, do not stop or change it. Bring the full list, including supplements, to the prescriber. Timing adjustments or alternatives often exist, and the decision belongs to them.

Lifestyle and environment: light, screens, schedules and the bedroom itself

For a large share of people, the honest answer to what causes lack of sleep is the shape of an ordinary day.

Light is the master signal. The body clock sits in a cluster of cells behind the eyes and sets itself by morning light; it expects dimness in the evening. Modern life inverts this: dim offices by day, bright screens and ceiling LEDs by night. Laboratory studies show evening light suppresses melatonin and delays its onset by an hour or more. Whether phone screens specifically are the villain is less settled than the headlines suggest (the content on the screen, and the hour it keeps you up, may matter as much as the wavelength), but the direction of effect is clear.

Irregular timing confuses the clock. Going to bed at 10 on weeknights and 2 a.m. on weekends, then sleeping until noon, produces what researchers call social jet lag; the Monday morning feels like a transatlantic flight because, biologically, it is. Shift work does this on an industrial scale, and rotating shifts are harder on sleep than fixed nights.

Napping is fine in short doses early in the afternoon; a 90-minute nap at 6 p.m. spends the sleep pressure you need at 11.

The bedroom matters in measurable ways. Core body temperature has to drop for sleep to begin, so a hot room (above about 75°F, or 24°C) is a reliable sleep thief; a cool one in the 60s Fahrenheit (around 16 to 19°C) suits most people. Noise causes arousals even when it does not wake you fully. Pets, snoring partners and small children are real and legitimate causes that no sleep hygiene list can fix.

Exercise improves sleep in randomised trials, especially for older adults and people with insomnia, though a very hard workout within an hour of bed can delay sleep onset for some. Heavy, late meals, and lying awake in bed for hours scrolling, round out the usual suspects.

Why am I waking up every 2 hours? Sleep cycles and the usual explanations

Waking every two hours or so is one of the most searched sleep complaints, and the first thing to know is that brief waking is built into normal sleep.

Sleep runs in cycles of roughly 90 to 120 minutes, moving from light sleep into deep slow-wave sleep and then into REM, the stage of vivid dreams and near-paralysed muscles. At the end of each cycle the brain surfaces briefly, checks the environment, and usually dives back down without laying down a memory. Four to six of these transitions a night is normal. What turns a transition into a full awakening is anything that makes the brain decide the coast is not clear.

The common culprits, roughly in order of frequency in clinic:

• Hyperarousal and conditioned insomnia: the brain surfaces at the end of a cycle and, trained by months of 3 a.m. frustration, snaps fully awake.
• Sleep apnea: breathing events cluster in REM sleep, which recurs at the end of each cycle, producing a wake-every-cycle pattern with snoring or gasping.
• Alcohol: the rebound arousal arrives three to four hours after the last drink, then repeats.
• Nocturia: a full bladder, or the conditions behind it, is a frequent reason for clock-like waking.
• Hot flashes, pain, reflux and restless legs, each with its own signature.
• Infant or child care, which rewires a parent’s sleep for years.
• Blood sugar swings in people with diabetes, and some medicines wearing off overnight.

A useful clue is what you notice on waking. Gasping or a pounding heart points toward apnea. Sweat points toward menopause, infection, alcohol, or an overactive thyroid. A busy mind points toward hyperarousal. Leg discomfort points toward restless legs. A full bladder every time points toward nocturia and its medical causes. Keeping a two-week sleep diary noting the wake time and the sensation is the single most helpful thing you can bring to a doctor.

What are the symptoms of sleep deprivation? How to tell it is hurting you

People are poor judges of their own sleepiness. In controlled studies where volunteers were restricted to six hours a night for two weeks, their reaction times and attention declined steadily to the level of someone kept awake for two full nights, yet their self-rated sleepiness plateaued after a few days. They felt “a bit tired.” Their performance said otherwise.

Short-term signs of sleep deprivation include:

• Irritability, low mood and a shorter fuse, often noticed by others first.
• Poor concentration, slowed thinking, more mistakes and forgotten words.
• Microsleeps: seconds-long lapses, dangerous behind the wheel. The CDC lists drowsy driving as a major contributor to crashes.
• Increased appetite, particularly for high-carbohydrate foods, because hormones regulating hunger (leptin and ghrelin) shift after short nights.
• Falling asleep within five minutes of lying down, or whenever still, which is a sign of deprivation rather than good sleeping.
• Headaches, heavy eyes, yawning, and a sense of “fog.”

The longer-term associations are drawn mostly from large observational studies, so they show links rather than proof of cause, but they are consistent across populations: habitual sleep under six or seven hours is associated with higher rates of high blood pressure, type 2 diabetes, obesity, depression, and reduced immune response, including weaker antibody responses after vaccination in several studies. The American Heart Association’s decision to include sleep in its cardiovascular health score rests on this body of evidence.

One distinction matters clinically. Sleep deprivation means you are not giving yourself enough opportunity to sleep; the fix is time. Insomnia means you have the opportunity and cannot use it. Many people with insomnia are not objectively sleepy in the daytime; they are fatigued and wired, which is one reason sedating daytime naps rarely help them and may make the night worse. If you can fall asleep easily in the afternoon, deprivation or another disorder is more likely than classic insomnia.

What the evidence actually says: grading the causes and the fixes

Not every claim in this field is equally solid. Here is a candid grading, using the standard hierarchy: randomised controlled trials (strongest), observational studies (associations, not proof), and expert opinion (weakest).

Strong, from randomised trials. Caffeine within six hours of bed shortens and lightens sleep. Alcohol fragments the second half of the night (demonstrated in laboratory sleep studies with controlled dosing). Cognitive behavioural therapy for insomnia, a structured program that retrains sleep habits and the thoughts around them, improves sleep in dozens of trials and is recommended as first-line treatment by major guidelines; benefits persist after the course ends, which no medicine has matched. Regular exercise improves sleep quality in trials, especially in middle-aged and older adults. Treating moderate-to-severe sleep apnea with airway pressure therapy reduces daytime sleepiness in trials.

Moderate, from experimental and observational data. Evening light delays melatonin and the body clock; the lab evidence is solid, while real-world screen studies are mostly observational and confounded by what people do on screens. Short habitual sleep is associated with heart disease, diabetes and obesity; the associations are consistent and biologically plausible, but trials proving that extending sleep prevents these outcomes are small and few. Menopausal hormone therapy improves sleep when night sweats are the main driver.

Weak or unproven. Magnesium supplements: the NIH Office of Dietary Supplements notes only a small number of short trials, mostly in older adults with low magnesium, and calls the evidence limited. Weighted blankets: a few small trials, mostly in psychiatric populations. Mouth taping: no good trials; expert bodies warn it can be unsafe for anyone with nasal blockage or undiagnosed apnea. Lavender, herbal teas, specific bedtime foods: largely small or low-quality studies.

A fair summary: the behavioural and timing causes have the best-tested solutions, the medical causes have specific treatments, and most of what trends online sits in the weakest tier.

Which kind of lack of sleep do you have? A quick comparison by pattern

Doctors read the pattern of a bad night the way a mechanic listens to an engine. The table below is not a diagnostic tool, but it shows how the timing of your sleeplessness narrows the likely causes and what a clinician would typically ask about next.

Pattern	Most likely cause clusters	Distinguishing clues	What a doctor usually checks first
Can’t fall asleep for 30+ minutes	Hyperarousal, anxiety, caffeine or nicotine, delayed body clock, restless legs	Racing thoughts; feels alert in bed; natural night-owl tendency; leg discomfort	Caffeine timing, evening light and screen use, mood screen, ferritin if legs restless
Waking every 2 hours	Sleep apnea, alcohol, nocturia, conditioned insomnia, pain or reflux	Snoring or gasping; drinks in the evening; full bladder each time; heartburn	Snoring history, alcohol diary, urinary symptoms, sleep study if apnea suspected
Early waking (3 to 5 a.m.), can’t return	Depression, advanced body clock with age, cortisol disturbance, alcohol rebound	Low mood; waking feels final; older age; evening drinking	Depression screen, light exposure timing, medicine review
Sleeps 7 to 8 hours, wakes unrefreshed	Sleep apnea, periodic limb movements, underactive thyroid, chronic pain, some medicines	Loud snoring; morning headache; dry mouth; partner sees leg kicks	Sleep study, thyroid blood test, medicine review
Sleep fine, but only at the wrong times	Circadian rhythm disorder, shift work, social jet lag	Weekend sleep differs by 2+ hours; feels normal on holiday	Sleep diary over two weeks, work schedule, light timing
Night sweats and repeated waking	Menopause transition, infection, overactive thyroid, alcohol, some antidepressants	Age 45 to 55 with cycle changes; fever; weight loss; heat intolerance	Menstrual history, temperature, thyroid test

Two caveats. Patterns overlap, and most people with chronic insomnia have more than one row ticked. And the table describes likelihoods, not certainties; a slim non-snorer can have apnea and a cheerful person can have depression. Use it to organise what you tell your clinician, not to replace them.

How to treat insomnia without medication: what works and why

Most people searching how to treat insomnia without medication expect a sleep-hygiene list. Sleep hygiene (a cool, dark room; no caffeine late; a wind-down routine) is sensible and helps mild cases, but trials show it is not enough on its own for established insomnia. What works is a specific program called cognitive behavioural therapy for insomnia, or CBT-I.

CBT-I is a short, structured therapy, usually four to eight sessions, delivered by a trained clinician, in groups, or through validated digital programs. It has four core components, and understanding them explains why it beats willpower.

Stimulus control reconnects bed with sleep. You go to bed only when sleepy, get up and do something quiet in dim light if you are awake for about 20 minutes, use the bed only for sleep and intimacy, and get up at the same time every day regardless of the night. It feels counterintuitive and it is the most effective single element.

Sleep restriction, better named sleep scheduling, temporarily shrinks the time you allow in bed to roughly match the sleep you are actually getting, then expands it as sleep consolidates. A week or two of this builds strong sleep pressure, and most people start sleeping more deeply before they sleep longer. It is done under guidance, and people with epilepsy, bipolar disorder or safety-critical jobs need a clinician’s oversight.

Cognitive work targets the thoughts that fuel hyperarousal: “If I don’t sleep eight hours I’ll be useless,” “I’ve lost the ability to sleep.” These are tested against evidence from the person’s own diary.

Relaxation and wind-down techniques, including slow breathing and progressive muscle relaxation, lower physiological arousal.

Randomised trials show CBT-I improves time to fall asleep, night-time waking and sleep quality, with effects that last a year or more after treatment. It also helps when insomnia coexists with pain, depression or menopause. Exercise, morning light, and a fixed wake time add to the effect. None of this replaces evaluation for apnea, restless legs or medical causes, which need their own treatment.

Common myths about lack of sleep, checked against the evidence

The viral feed is a myth factory. Here are the claims that come up most, and what the evidence says.

“Alcohol helps you sleep.” It helps you fall asleep and then wrecks the second half of the night: lighter sleep, more awakenings, suppressed REM, more snoring. Laboratory studies are consistent. A nightcap is a cause of lack of sleep, not a remedy.

“Older adults need less sleep.” Sleep need stays around seven to eight hours into old age. What changes is the ability to get it in one block; sleep becomes lighter and more fragmented, and the body clock drifts earlier. Accepting four hours as normal aging can hide treatable causes such as apnea, pain or nocturia.

“If you can’t sleep, stay in bed and rest.” Trials of stimulus control show the opposite: lying awake trains the brain to associate bed with wakefulness. Getting up briefly and returning when sleepy works better.

“You can catch up at the weekend.” You can repay some of the debt to alertness, but long weekend lie-ins shift the body clock and create the Monday social-jet-lag crash. Studies of weekend recovery sleep find metabolic measures do not fully normalise.

“Mouth taping fixes snoring and sleep.” There is no good trial evidence for it in healthy adults, and for anyone with nasal congestion or undiagnosed sleep apnea, restricting the mouth can be unsafe. Snoring loud enough to want tape is a reason for a sleep assessment, not adhesive.

“Magnesium drinks are the answer.” The NIH Office of Dietary Supplements describes the evidence for magnesium and sleep as limited, from small short trials, mostly in older adults with low levels. Supplements also interact with some medicines; discuss them with a pharmacist or doctor.

“Blue-light glasses are essential.” Evening light does delay melatonin, but the real-world benefit of tinted lenses is modest and mixed in trials. Dimming lights and stopping stimulating activity an hour before bed addresses the same mechanism without purchases.

“Everyone needs eight hours.” The healthy range for adults is seven to nine; a minority function well on slightly less or need slightly more. Daytime function, not a number, is the test.

When to see a doctor about lack of sleep: red flags and what to bring

Short spells of poor sleep around a stressful event are normal and usually settle. Make an appointment when sleep problems occur three or more nights a week for a month or more, when they are affecting your mood, work or safety, or when any of the following accompany them.

Seek prompt medical advice if you notice:

• Loud snoring with witnessed pauses in breathing, gasping or choking at night, or waking with a headache, which can indicate sleep apnea.
• Falling asleep unintentionally during the day, especially while driving, in conversation or at work. Do not drive if you are struggling to stay awake.
• Chest pain, breathlessness when lying flat, or a racing or irregular heartbeat at night.
• Night sweats with fever, unexplained weight loss, or a new lump, which need evaluation for infection or other illness.
• Persistent low mood, loss of interest, hopelessness, or any thoughts of harming yourself. In the United States, you can call or text 988 at any time.
• Acting out dreams, violent movements, or injuring yourself or a partner during sleep.
• New confusion, memory problems or sleepiness in an older adult.
• Sleep problems that began after starting a new medicine; do not stop it yourself, ask the prescriber.
• Waking two or more times a night to urinate, new leg sensations in the evening, or heartburn most nights.

Bring a two-week sleep diary (bedtime, estimated time to fall asleep, number and timing of awakenings, wake time, caffeine, alcohol, naps and how you felt), a full list of medicines and supplements, and if possible a bed partner’s observations. Your clinician may order blood tests, a sleep study, or refer you for CBT-I.

Every decision about medicines, including over-the-counter sleep aids, melatonin and supplements, belongs with your prescribing clinician, who can weigh your history and other medicines. This article explains causes and evidence; it cannot diagnose you or tell you what to take.

Frequently asked questions

Why can't I sleep even though I'm exhausted?

The most common reason is hyperarousal: a nervous system running on high alert that produces the “tired but wired” feeling. Stress, anxiety, evening caffeine, late light exposure and the learned habit of lying awake in bed all feed it. Fatigue and sleepiness are different states; you can be deeply fatigued yet not sleepy. If this lasts more than a few weeks, cognitive behavioural therapy for insomnia addresses exactly this pattern, and a clinician can rule out medical causes.

What causes lack of sleep in women around midlife?

The menopause transition is the leading cause of new sleep problems in women in their late 40s and 50s. Falling estrogen destabilises temperature control, producing hot flashes and night sweats that repeatedly wake people, and the hormonal shift also affects mood and sleep-regulating brain regions. Sleep apnea becomes more common after menopause too and is often missed in women. Whether hormone therapy or other treatments suit you is a decision for your clinician based on your history.

What are the possible reasons for waking up every 2 hours?

Normal sleep runs in 90-to-120-minute cycles with a brief surfacing at the end of each; something is turning those surfacings into full awakenings. Common reasons include sleep apnea, alcohol in the evening, a full bladder from nocturia, conditioned insomnia, hot flashes, pain, reflux and restless legs. What you notice on waking (gasping, sweating, a busy mind, leg discomfort, a full bladder) is the best clue, so note it in a diary for your doctor.

What are the symptoms of sleep deprivation?

Irritability, poor concentration, slowed reactions, forgotten words, increased appetite for carbohydrate-rich foods, heavy eyes, and falling asleep within minutes whenever you sit still. Microsleeps, lasting a few seconds, are the most dangerous sign and a major factor in drowsy-driving crashes. In studies, people restricted to six hours a night stopped feeling sleepier after a few days while their performance kept declining, so feeling “fine” is not reliable evidence that you are getting enough sleep.

How can I treat insomnia without medication?

Cognitive behavioural therapy for insomnia (CBT-I) is the first-line treatment in major guidelines and has the strongest trial evidence. It combines getting out of bed when awake, a fixed wake time, temporarily matching time in bed to actual sleep, challenging catastrophic thoughts about sleep, and relaxation. Regular exercise, morning daylight and limiting caffeine and alcohol add to the effect. It is delivered by trained clinicians, in groups or via validated digital programs, and works alongside treatment of any medical causes.

Can a medical condition be the reason for not sleeping at night?

Yes, and clinicians look for these first. Chronic pain, acid reflux, an overactive or underactive thyroid, asthma, heart failure, an enlarged prostate or overactive bladder, diabetes, allergies, itchy skin conditions, and neurological diseases such as Parkinson’s all disturb sleep. Sleep disorders themselves, especially obstructive sleep apnea and restless legs syndrome, are frequently undiagnosed. If your sleeplessness arrived with a new physical symptom, that symptom is the place to start the conversation.

Which medicines can cause lack of sleep?

Several classes are associated with insomnia or fragmented sleep: some antidepressants, corticosteroids, beta blockers, stimulants used for attention deficit disorder, decongestants, some asthma medicines, diuretics taken late in the day, and thyroid hormone when the level runs high. Over-the-counter “PM” antihistamines can leave a hangover and lose effect quickly. Never stop or adjust a prescribed medicine on your own; bring the full list, including supplements, to your prescriber, who may adjust timing or suggest alternatives.

Does lack of sleep cause weight gain or heart problems?

Large observational studies consistently link habitual short sleep with higher rates of obesity, type 2 diabetes, high blood pressure and heart disease, which is why the American Heart Association added sleep to its cardiovascular health score in 2022. Short-term experiments show sleep loss shifts appetite hormones and increases calorie intake. These data show strong associations and plausible mechanisms; trials proving that extending sleep prevents these diseases are still small, so the honest grade is moderate evidence.

What are some interesting facts about sleep?

The brain clears metabolic waste more efficiently during deep sleep. Core body temperature has to fall for sleep to start, which is why a hot room is such a reliable sleep thief. Most people briefly wake four to six times a night without remembering it. Teenagers’ body clocks genuinely run later, a biological shift, not laziness. And people with chronic insomnia often overestimate how long they lie awake, a finding that itself becomes part of CBT-I treatment.

When should I see a doctor about not sleeping?

See a doctor if poor sleep happens three or more nights a week for a month or more, or sooner if you have loud snoring with gasping or breathing pauses, fall asleep unintentionally in the day, have chest pain or breathlessness lying flat, night sweats with fever or weight loss, persistent low mood or thoughts of self-harm, or act out dreams. Bring a two-week sleep diary and your medicine list; your clinician may arrange blood tests, a sleep study or CBT-I.

References

• Insomnia: Causes and Risk Factors (NHLBI, National Institutes of Health)
• Insomnia (NHS)
• About Sleep (Centers for Disease Control and Prevention)

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.