How Does Sleep Affect Long-Term Health?

Medical Writer: Judith Ewere Ojerahi RN, RM, RPHN, BNSC

Medical Reviewer: Oke Ikpekpe, MSc (PH)

Highlights 

• Sleep is an active biological process where the body rests while the brain and body carry out important functions. 
• During sleep, the brain stays active, repairing the body, processing memories, and regulating hormones.
• Poor sleep over time can lead to serious health issues such as obesity, heart disease, anxiety, and depression.
• Lack of sleep affects concentration, mood, memory, and overall productivity.
• Adults typically need 7–9 hours of sleep, while teenagers require 8–10 hours for proper development and recovery.
• Good sleep can be improved through simple habits like consistent sleep schedules, reduced screen time, stress management, and a better sleep environment.

Introduction 

Sleep is more than just rest. A lot happens in your body while you sleep. Have you ever wondered why we fall asleep? Why do our bodies automatically know when to sleep and wake up most times without an alarm? It is your circadian rhythm that makes this possible. When your body needs sleep or wakes up, it serves as an internal alarm clock that starts and ends your sleep time. 

Sleep is when your body is resting and inactive, but the brain is functioning and responding to outside influences. It is a therapy that has many effects on our lives. Proper sleep assists with brain functions, good control of emotions, concentration, and general well-being. If you are always sleep deprived, you may feel emotionally, physically, and mentally exhausted. When you do not get enough sleep over time, it can affect how you think, feel, work, and respond to daily activities.

In this article, you will understand why we sleep, what happens when we sleep, and simple things you can do to improve your sleep.

Why Do We Sleep?

Sleep is a natural and active biological process. While the body rests, the brain continues to respond to certain signals and carry out important functions [1]. This is why you may still respond to certain sounds, touch, or changes in your environment while asleep. Sleep is an essential part of human life, and the reasons why we sleep include the following:

• Attention: Having a good night's sleep helps you focus and concentrate when performing tasks. Sleep helps to stabilise the brain.

• Memory: Adequate sleep before and after learning helps the brain process and retain new information.

• Emotion: Sleep helps regulate your emotions. When you get enough sleep, you can process, interpret, and respond to emotional stimuli.

• Daytime performance: When you sleep well at night, you are able to stay alert and respond well to difficult situations. Sleep promotes decision making, coordination, and balance [2].

What Happens When You Sleep?

Sleep starts with two systems; the homeostatic sleep drive and the circadian rhythm.

• The homeostatic sleep drive is the pressure to sleep that builds up the longer you stay awake. 
• The circadian rhythm is your body’s internal clock that helps regulate when you feel awake and when you feel sleepy. 

A hormone called melatonin is produced in the body, which controls the circadian rhythm. Melatonin levels usually increase in darkness and decrease with exposure to light. 

Hence, the hormone is more present at night and less present during the day. That is why you feel more sleepy at night. 

There are two stages of sleep. 

• Non-rapid eye movement (NREM): This stage is characterized by the absence of eye movements during sleep, and it includes the lighter and deeper stages of sleep. It is divided into 3 stages.

NREM stage 1: This is the lightest stage of sleep and usually lasts for 1 to 7 minutes before going into stages 2 and 3

NREM stage 2: This is a light sleep stage where the heart rate slows, and body temperature begins to drop.

NREM stage 3: Deep sleep occurs mainly during this stage. It supports physical recovery, tissue repair, and immune function.

• Rapid eye movement (REM): It is a stage where the eyes move quickly, brain activity increases, and dreaming occurs.

While we are asleep, many biological processes take place.

 They include: 

• Repairing of muscles 
• Growth of tissues
• Release of various hormones used in growth and body metabolism [1].

Some factors can disrupt the circadian rhythm, leading to poor sleep. 

Some include:

• Working on jobs that require you to work at night
• Not sleeping at a particular time at night
• Irregular eating patterns 
• Screen use close to bedtime 
• Sleeping in a room with lights on [8].

How Poor Sleep Affects Long-Term Health

Poor sleep may involve sleeping for a short period of time, waking up often, difficulty falling asleep, waking too early, or sleeping at irregular times, which reduces the quality of your sleep. When poor sleep continues over time, it can affect physical health, mental well-being, and daily functioning.  Some of these effects can make falling asleep difficult for you. Not getting enough sleep, especially at night, can lead to:

1. Cardiovascular effects: Poor sleep can contribute to an increase in blood pressure, leading to hypertension, especially if you are at risk of getting hypertension. 
2. Metabolic effects: During sleep, our bodies regulate hormones and blood sugar. Poor sleep over time may affect how the body responds to insulin and may increase the risk of type 2 diabetes, especially when combined with other risk factors. 
3. Weight gain: Poor sleep may affect appetite hormones, food choices, energy levels, and blood sugar regulation. Over time, these changes can contribute to weight gain. 
4. Mood and emotional changes: Sleep helps with emotional regulation. Poor sleep can make it harder to manage stress and emotions. It may increase irritability, anxiety, low mood, poor concentration, and reduced attention span  [3,4].
5. Cognitive decline: When you don't sleep well, it can lead to a decline in brain function. You may not be able to think properly, make decisions, or even respond well to things around you. It may increase your risk of getting neurodegenerative conditions like Parkinson’s disease and Alzheimer's disease [2].
6. Immune function: Sleep also supports immune function. When you do not get enough quality sleep, your body may not respond as well to infections or recovery. 
7. Accidents and safety: Poor sleep can also affect safety. It can slow reaction time and increase the risk of mistakes, road accidents, and workplace injuries. 

Signs You May Not Be Getting Enough Sleep

When you don't get enough sleep, your body shows signs. Some of these signs include:

• Sleeping during the day, which interferes with daily activities.
• Feeling tired most of the time.
• Being irritable.
• Not being able to focus and pay attention.
• Responding slowly to external reactions.
• Headaches.
• Microsleeps 
• Finding it hard to speak clearly.
• Inability to make decisions.

How Much Sleep Do You Really Need?

Sleep is very important for your health. The American Academy of Sleep Medicine (AASM) and the Sleep Research Society (SRS) recommended the amount of sleep adults need regularly.

• Adults should have at least 7 hours of sleep every night. 
• Younger adults or teenagers should sleep for at least 9 hours at night [5].

Children and adolescents should get enough sleep in order to help with their growth and development. 

The recommended amount of sleep according to the consensus statement of the American Academy of Sleep Medicine includes the following:

• Infants aged 4 months to 12 months should have at least 12 to 16 hours of sleep daily.
• Children aged 1 to 2 years are required to get 11 to 14 hours of sleep daily.
• Children aged 3 to 5 years, they are required to have 10 to 13 hours of sleep daily
• Children aged 6 to 12 years should have at least 9 to 12 hours of sleep regularly to maintain overall health and well-being [6].

Simple Ways to Improve Your Sleep

Sleep hygiene refers to ways you can have healthy sleep. It involves managing your environment and improving your activities before bedtime [7]. Some of the things you can do to improve your sleep include:

• Avoid taking alcohol, coffee, energy drinks, or anything that has caffeine in it before sleeping.
• Staying active and exercising regularly during the day can help you sleep at night.
• Ensure you sleep in a cool, dark, and quiet room. Sleeping in a room that is too hot or too cold can make you feel very uncomfortable sleeping.
• Keep a regular bedtime by going to bed and waking up around the same time each day, including weekends when possible. 
• Turn off your phone or TV an hour before you sleep. 
• Sleeping in cotton nightwear enhances your sleep. This is because cotton nightwear can adjust to temperature changes.
• Use a comfortable bed and pillow [8].

When To Seek Help

If you have difficulty sleeping for several weeks, or if you snore loudly, wake up gasping, or feel extremely sleepy during the day, speak with a healthcare professional. These may be signs of an underlying sleep disorder.

Conclusion

Sleep is a fundamental requirement for healthy living that supports both the mind and body in significant ways. It supports cognitive performance, emotional stability, and physical restoration, while insufficient sleep can disrupt normal functioning and reduce overall well-being. Having a good night's sleep regularly is a powerful step towards better health, sharper thinking, and improved quality of life.

References 

1. Brinkman JE, Reddy V, Sharma S. Physiology of sleep. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan–. Updated 2023 Apr 3 [cited 2026 May 22]. Available from:https://www.ncbi.nlm.nih.gov/books/NBK482512/

2. Hyndych A, El-Abassi R, Mader EC Jr. The role of sleep and the effects of sleep loss on cognitive, affective, and behavioral processes. Cureus. 2025;17(5):e84232. Available from:https://pmc.ncbi.nlm.nih.gov/articles/PMC12168795/

3. Hanson JA, Huecker MR. Sleep deprivation. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan–. Updated 2023 Jun 12 [cited 2026 May 22]. Available from:https://www.ncbi.nlm.nih.gov/books/NBK547676/

4. Shah AS, Pant MR, Bommasamudram T, Nayak KR, Roberts SSH, Gallagher C, et al. Effects of sleep deprivation on physical and mental health outcomes: an umbrella review. Am J Lifestyle Med. 2025. Available from:https://pmc.ncbi.nlm.nih.gov/articles/PMC12116485/

5. Watson NF, Badr MS, Belenky G, Bliwise DL, Buxton OM, Buysse D, et al. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep. 2015;38(6):843-4. Available from:https://pmc.ncbi.nlm.nih.gov/articles/PMC4434546/

6. Sundell AL, Angelhoff C. Sleep and its relation to health-related quality of life in 3-10-year-old children. BMC Public Health. 2021;21:1043. Available from:https://link.springer.com/article/10.1186/s12889-021-11038-7

7. Pfeiffer AM, Triplett C, Schaefers O. Improving sleep health through sleep hygiene education in adults aged 50-80 years. Front Sleep. 2026;4:1722557. Available from:https://pmc.ncbi.nlm.nih.gov/articles/PMC12848612/#B19

8. Chow CM. Sleep hygiene practices: where to now? Hygiene. 2022;2(3):146-51. Available from:https://doi.org/10.3390/hygiene2030013

Disclaimer:
The information provided on this website is for general educational and informational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Published May 30, 2026