Why Can’t You Think Straight After a Sleepless Night?


Written by Katherine Zheng

Reviewed by Dr. Michael Breus

Our Editorial Process

Table of Contents

It’s no secret that getting enough sleep is important for staying healthy and feeling your best. If you’ve ever had a restless or sleepless night, you probably know some of the cognitive effects of sleep loss, like grogginess, sleepiness, and difficulty concentrating. 

While it’s important to get enough sleep each night, it’s not always easy. Poor sleep habits, medical issues, and obligations at home, work, or school often make it hard to get enough rest. After a sleepless night, it can be helpful to understand why it may be hard to think straight and what you can do to manage your symptoms.

How Does Feeling Tired Affect Concentration?

Without enough sleep, your brain cells do not work as efficiently and you may have trouble concentrating. Additionally, losing a night of sleep can leave you feeling so tired that you stop paying attention to what’s around you and have short lapses into sleep, an experience that experts call microsleeps.

Billions of brain cells called neurons send signals around the body to help you carry out important functions like thinking and feeling emotions. After being so active throughout the day, these cells need time to rest at night in order to be refreshed and function well again the next morning. 

Even one night of poor sleep can lead to tiredness and difficulty concentrating the next day. A sleepless night can make it more challenging to:

  • Form sentences
  • Process information
  • Recall information from memory
  • Make judgments
  • Focus on multiple tasks or goals

Even when the effects of sleep loss are not immediately noticeable, they can significantly affect your ability to think straight and concentrate during the day. For instance, after a sleepless night you may have more difficulty focusing while driving, not learn as well at school, or make more errors at work. 

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How Else Does Sleep Deprivation Affect You?

Beyond impacting the way you think and your ability to concentrate, sleep deprivation can have many other negative effects.

  • Mood: A lack of sleep can lead to irritability, lower energy, and symptoms similar to anxiety or depression.
  • Health: Consistently not getting enough sleep can contribute to certain medical conditions, including obesity, cardiac disease, and high blood pressure. 
  • Immunity: A lack of sleep can weaken your immune system, making you more prone to catching a cold or flu and less responsive to vaccinations.
  • Social life: Without proper sleep, you may have less energy to see friends, spend time with family, or enjoy hobbies and leisure activities.
  • Growth and development: If you’re a child or teen, sleep is important as you develop into an adult. Sleep problems can interfere with your healthy development.

How Much Sleep Do You Need?

Different factors determine the amount of sleep you need each night, including your age, level of physical activity, health, recent sleep habits, and even your genetics. Experts provide general recommendations for sleep based on the age group you are in.

Age GroupAge RangeRecommended hours of sleep per 24 hours, including naps
Newborns 0-3 months14-17 hours
Infants4-11 months12-15 hours
Toddlers1-2 years11-14 hours
Preschoolers3-5 years10-13 hours
School-aged children6-13 years9-11 hours
Teenagers14-17 years8-10 hours
Young adults18-25 years7-9 hours
Adults26-64 years7-9 hours
Older Adults65 years and over7-8 hours

In addition to getting enough sleep, it’s important to get good quality sleep. Your sleep quality may be poor if you wake up regularly at night or don’t get enough of certain sleep stages. There are four stages of sleep that your brain cycles through every night. If any of these stages are interrupted during the night, you are more likely to wake up feeling tired.

What Should You Do if You’re Tired and Can’t Concentrate?

Although there is no replacement for sleep, there are remedies you can try at home to help you feel more alert on days where you have to focus despite getting inadequate or poor quality sleep.

  • Exercise: Getting physical activity helps the brain release chemicals called endorphins, which boost your mood. Exercise can also help you feel more energized.
  • Get some light: Getting direct light exposure from the sun, or even artificial sources like a bright light box, can help your body feel more awake.
  • Stay hydrated: Dehydration can make you feel more tired and sleepy, so it is important to get enough water intake throughout the day.
  • Caffeine: Caffeine found in coffee or tea can give you a boost of energy to help you focus. However, you should take caffeine in moderation and only in the first half of the day, to avoid having another sleepless night.
  • Take a short nap: If your schedule allows for it, taking a 15- to 30-minute nap early in the day may help you feel more refreshed and focused.

How to Improve Your Sleep

The most important way to improve your sleep is to prioritize your sleep health and set aside enough time for sleep each night. While you may not be able to control your schedule all the time, there are other ways that you can improve the quality of your sleep. 

You may want to begin by identifying your reasons for not getting enough sleep. To learn about your sleep habits, try starting a sleep diary where you can document things like your daily mood, diet, activities, and sleep patterns.

Some common causes of poor sleep include:

  • Increased stress or anxiety
  • Excessive noise or lights where you sleep
  • Lack of physical activity during the day
  • Excessive alcohol or drug use
  • Too much caffeine late in the day
  • Taking naps too close to bedtime

Improving your sleep hygiene can help combat these causes of sleep loss and promote restful sleep. Sleep hygiene refers to all the habits you carry out before and during bedtime. 

Examples of good sleep hygiene include:

  • Avoiding the use of electronics before bedtime
  • Only using your bed for sleep and sex, not other activities like work or watching TV
  • Avoiding large meals, coffee, and alcohol before bedtime
  • Increasing physical activity and light exposure during the day
  • Incorporating relaxation activities, such as deep breathing, before bed
  • Keeping your bedroom environment dark, quiet, and cool at bedtime

When to Seek Help From a Doctor

While it’s normal to have trouble sleeping sometimes, speak with your doctor if you regularly feel tired or if problems with thinking begin to affect your daily life. A health care professional can provide a thorough assessment of your concerns and offer a treatment plan that best suits your needs.

About The Author

Katherine Zheng

Staff Writer, Sleep Health

Katherine is a freelance writer based in Chicago. She has doctorate and bachelor’s degrees in nursing and is published in the journal Administration and Policy in Mental Health and Mental Health Services Research and the journal JMIR Mental Health. She has also worked as a policy fellow at Northwestern University Feinberg School of Medicine. With a background in academia, Katherine has always been interested in making healthcare research more accessible to the public. When not writing, Katherine is an actor and loves doing theater at night.

  • POSITION: Side Sleeper
  • TEMPERATURE: Neutral Sleeper
  • CHRONOTYPE: Dolphin

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