Insomnia
Insomnia is more than one rotten night: it has a formal yardstick of three nights a week for three months.
By Greg Goodwin · Published November 4, 2026
Cheat Sheet
- Chronic threshold: 3 or more nights a week, for more than 3 months, and not fully explained by another health problem (NHLBI).
- Short-term insomnia can last a few days or weeks.
- Adult sleep recommendation (CDC): 7 or more hours at ages 18 to 60, 7 to 9 hours at 61 to 64, and 7 to 8 hours at 65 and older.
- Teen recommendation (CDC): 8 to 10 hours at ages 13 to 17.
- Who gets it: possible at any age, with chances rising as you get older, and more common in women than in men (NHLBI).
- Clinic tool: a sleep diary can log bedtime, night wakings, naps, exercise, alcohol or caffeine and medications (CDC).
The 60-Second Version
Insomnia is a common sleep disorder in which you have trouble falling asleep, staying asleep, or getting good quality sleep, even when you have the time and a suitable environment for it. It can leave you sleepy during the day and can affect memory and concentration. Stress or a change in schedule or surroundings can set off short-term bouts, while chronic insomnia is the longer-running form that is not fully explained by another health problem. Risk factors run from age and family history to shift work, noise, light, caffeine and even worrying about whether you will get enough sleep. To work out what is going on, a healthcare provider may ask about your sleep habits and have you keep a sleep diary, and can discuss ways to manage it. Everyone has rough nights; insomnia is the pattern that persists and gets in the way of daily activities. This page is general information, not medical advice. If you regularly have trouble sleeping, talk to a healthcare provider.
The Long Version
What Counts as Insomnia
The National Heart, Lung, and Blood Institute describes insomnia as trouble falling asleep, staying asleep, or getting good quality sleep, even if you have the time and the right environment to sleep well. It can get in the way of daily activities and make you sleepy during the day. The institute separates two forms. Short-term insomnia may be caused by stress or changes in your schedule or environment and can last a few days or weeks. Chronic insomnia occurs 3 or more nights a week, lasts more than 3 months, and cannot be fully explained by another health problem. The CDC adds that signs of poor sleep quality include trouble falling asleep, repeatedly waking during the night, and feeling tired even after enough hours.
Who Gets It and Why
NHLBI says you can develop insomnia at any age, but the chances increase as you get older. Family history matters: insomnia sometimes runs in families, and genes may also affect whether you are a deep or light sleeper. Environment and occupation can disturb your sleep-wake cycle, including shift or night work, noise or light during the night, uncomfortable temperatures and frequent travel across time zones. Lifestyle habits such as changing your routine often, long daytime naps, little physical activity, and using caffeine, nicotine or alcohol can raise risk. Stress is another factor, and so is watching the clock. Insomnia is more common in women than in men, and hormone changes during pregnancy and menopause can cause sleep problems.
How Much Sleep Is Enough
The CDC lists recommended daily sleep by age. Teens aged 13 to 17 are advised to get 8 to 10 hours, adults aged 18 to 60 get 7 or more hours, adults 61 to 64 get 7 to 9 hours, and adults 65 and older get 7 to 8 hours. The agency also stresses that quality counts, not only the number of hours: quality sleep means getting uninterrupted and refreshing sleep. Because needs change with age and differ between people, a single magic number is less useful than noticing whether your sleep is restful and whether you function well the next day, which is the question a provider will usually come back to.
Why It Matters Beyond Feeling Tired
NHLBI notes that insomnia can affect your memory and concentration, and that chronic insomnia raises your risk of high blood pressure, coronary heart disease, diabetes and cancer. The CDC more broadly lists benefits of getting enough sleep: getting sick less often, staying at a healthy weight, reducing stress and improving mood, improving heart health and metabolism, lowering the risk of chronic conditions, and lessening the risk of motor vehicle crashes. None of this means one bad night is dangerous. It does explain why health agencies treat persistent sleep trouble as a topic worth raising with a professional, rather than something to simply tough out.
Getting It Evaluated
To diagnose insomnia, NHLBI says a healthcare provider may ask about your sleep habits and ask you to keep a sleep diary. The CDC describes the diary as a log of when you go to bed, wake during the night, wake in the morning, nap, exercise, drink alcohol or caffeinated drinks, and take medications. The CDC also notes that providers can run tests, including sleep studies, to tell whether you have a sleep disorder, and that other common sleep disorders include restless legs syndrome, narcolepsy and sleep apnea. NHLBI says a provider may recommend options such as a regular sleep schedule, cognitive behavioral therapy for insomnia, and medicines. Choosing among them is a clinical decision for you and your provider.
Why People Care
Sleep touches memory, mood and daily safety, so a lasting pattern of poor sleep is worth understanding. Knowing the difference between a rough week and chronic insomnia helps you decide when to raise it with a professional. This is general information, not medical advice.
Glossary
- Chronic insomnia
- Insomnia that occurs 3 or more nights a week, lasts more than 3 months, and cannot be fully explained by another health problem.
- Short-term insomnia
- Insomnia that can last a few days or weeks, often tied to stress or changes in schedule or environment.
- Sleep diary
- A log of sleep habits, such as bedtime, night wakings, naps and caffeine, that a provider may ask you to keep.
- Sleep quality
- How uninterrupted and refreshing your sleep is, which matters as well as the number of hours.
- Cognitive behavioral therapy for insomnia
- A type of therapy that NHLBI lists among the options a healthcare provider may recommend for insomnia.
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