Lack of Sleep Effects: Can It Make You Sick?

Key Takeaways

• Lack of sleep makes the body more vulnerable to infections by weakening immune responses.
• Chronic poor sleep is linked to both short-term and long-term chronic health issues. 
• More serious health issues linked to poor sleep include heart disease, obesity, diabetes, and worsened allergies.

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Skimping on sleep leaves us feeling groggy at best. Sleep is crucial in keeping our immune systems strong and ready to fight infections. When we don’t get enough rest, our bodies become more vulnerable to colds and other serious illnesses.

Here's everything you need to know about the effects of sleep deprivation on your immune system and why getting good sleep — both in quantity and quality — is essential to keep your body's defenses strong.

Sleep and the Immune System

While you sleep, your body goes into repair mode, producing infection-fighting proteins called cytokines. These proteins help your immune system respond to threats like viruses and bacteria. When you skimp on sleep, your body produces fewer cytokines, making it harder to fend off illness. 

Sleep also boosts the production of white blood cells, which act as your body’s defense army, attacking harmful invaders. Without enough rest, this army weakens, leaving you more exposed to infections. ¹ 

Chronic sleep deprivation can also lead to long-term immune system problems. Studies show that people who consistently get less sleep are more likely to catch infectious diseases like the common cold. And over time, lack of sleep can contribute to inflammation, making you more susceptible to serious conditions, such as heart disease and type 2 diabetes. ²

6 Health Issues Associated with Insufficient Sleep  

When you don't sleep enough on a consistent basis, your immune system takes a hit and leaves you susceptible to illness and more serious chronic diseases. It's important to note that the more serious health issues don't come up after a few restless nights here and there — it's more likely if you struggle to get good quality sleep regularly.

Common Cold

Lack of sleep makes it harder for your body to fight off infections, which can be especially problematic around cold and flu season. Research shows that people who get less than seven hours of sleep each night are about three times more likely to catch a cold than those who sleep 8 or more hours. Even small, habitual sleep disturbances (which the study defines as 10 to 38 minutes per 8 hours of sleep) are associated with a nearly four times greater risk of developing a cold. ³

What's more, research shows that people who slept only 4 hours a night for six days produced over 50% fewer antibodies after a flu vaccination compared to those with regular sleep. Even after a week of extra sleep, their immune response remained lower. ⁴

Depression and Mood Issues

Ever notice how you feel extra snappy and irritable after a poor night's sleep? It's not all in your head — sleep deprivation affects the brain’s ability to regulate emotions, making mood swings and irritability more common. And chronic bad sleep can raise your risk of developing a mood disorder such as depression, anxiety, or bipolar disorder. ^{5 6}

Obesity

Not getting enough sleep can throw off hunger-regulating hormones, which can contribute to increased cravings for unhealthy foods. Research shows that one effect of sleep deprivation is snacking more the following day, particularly on fatty, carb-rich foods.  

Here's why: Sleep deprivation is linked to higher levels of the hormone ghrelin (which makes you feel hungry) and lower levels of leptin (which signals fullness). And this all increases the risk of weight gain and obesity if you're chronically sleep-deprived. If your goal is weight loss or maintaining a healthy weight, getting better sleep should be a priority. ⁷

Type 2 Diabetes

Poor sleep causes your body to struggle to regulate blood sugar levels, which can contribute to insulin resistance. Over time, this can lead to a higher risk of developing type 2 diabetes. But it's also a catch-22 — if you already live with type 2 diabetes, the condition can cause sleep issues and make it harder to manage it. ⁸

Heart Disease

Consistently getting too little sleep is associated with high blood pressure, inflammation, and stress, which can all increase the risk of cardiovascular disease. In fact, a study in the journal Open Heart shows that people had a higher chance of getting a heart attack 3 to 4 days after losing sleep due to daylight savings time. Meanwhile, people have a lower chance of getting a heart attack when clocks fall back, and we gain an extra hour of sleep. ⁹

Allergies

Sleep helps control inflammation, which plays a role in allergies. When you don’t get enough rest, your body may struggle to manage allergic reactions. A study in the Journal of Allergy and Clinical Immunology found that sleep deprivation made people with peanut allergies more likely to have a reaction. ¹⁰

Is a Sleep Disorder to Blame?

Sometimes, trouble sleeping isn’t just about bad habits or a busy schedule — it could be a sign of a sleep disorder. Sleep disorders affect millions of people and can make it difficult to get the rest your body needs, putting you at risk of getting sick or developing serious health issues over time. If you’re constantly feeling tired, a sleep disorder might be the culprit. Here are some common ones to know about:

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• Insomnia: This is one of the most common sleep disorders, making it hard to fall asleep, stay asleep, or both. Insomnia can be short-term due to stress or long-term, affecting daily life and increasing the risk of health problems.
• Sleep Apnea: A serious condition where breathing repeatedly stops and starts during sleep. If left untreated, obstructive sleep apnea can lead to poor sleep quality, excessive daytime fatigue, and even an increased risk of heart disease, heart failure, and stroke. ¹¹

• Narcolepsy: A neurological disorder that disrupts the brain’s ability to regulate sleep-wake cycles, causing excessive daytime sleepiness and sudden “sleep attacks.” Some people with narcolepsy may also experience muscle weakness triggered by strong emotions. People with narcolepsy have a higher risk of heart disease and other heart issues. ¹²

• Restless Legs Syndrome (RLS): A condition that causes uncomfortable sensations in the legs and an irresistible urge to move them, often worsening at night and making it hard to fall asleep.
  

If you think you have a sleep disorder, talk to your doctor about it. Treating sleep disorders can greatly improve sleep quality, energy, immunity, and overall health.

The Bottom Line

Getting enough sleep is essential for a strong immune system and overall health, helping to protect against illnesses like colds, heart disease, and even allergies. Chronic sleep deprivation can lead to serious health issues, but prioritizing healthy sleep habits, such as maintaining a regular sleep schedule, creating a restful environment, and avoiding big meals before bed, can make a big difference in both your short-term and long-term health. If you struggle to fall asleep or stay asleep, or you find that you often wake up tired, consider talking to a healthcare provider about ways to help get your sleep schedule on track. 

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