Scientists Explain What Really Happens To Your Body If You Sleep Less Than 6 Hours A Night

Most of us know that a solid night of rest is important, but plenty of people struggle to get it, and researchers have now shared what actually happens to your body when you don’t.

Missing sleep occasionally may not have a huge impact, but consistently sleeping too little—or only in short bursts—can take a toll on both your body and your mind over time.

Speaking to Metro, Dr. Sue Peacock, a consultant health psychologist and sleep expert, pointed out just how damaging it can be to regularly get six hours of sleep or less each night.

If you’re dragging yourself through your days in a fog because you’ve gotten used to too little sleep, it might be time to call it a night earlier and give your body a chance to catch up on much-needed rest.

Immune System

Your immune system works hard around the clock to protect you, but running on too little sleep makes that job a lot harder.

Peacock explained: "Research shows that there is a complex link between sleep-wake cycles and our immune systems."

"While you sleep, your immune system produces protective, infection-fighting substances such as cytokines. It uses these substances to combat foreign invaders such as bacteria and viruses."

Getting minimal sleep is not great for your health Maria Korneeva/ Getty

"These cytokines also help you sleep, giving your immune system more energy to defend your body against illness."

She further explained that when you aren’t sleeping enough, your body fails to produce enough cytokines, leaving you more vulnerable to infections and illness than you may realize.

She also warned: "It increases our vulnerability to disease, and it may take you longer to recover from illness."

On top of this, scientists at the French National Institute carried out a 2023 study showing that sleeping less than six hours a night actually weakens the immune system’s response to vaccines.

Getting less than six hours sleep can cause anxiety among other things Justin Paget / Getty

Immune response to vaccinations

The research re-analyzed seven studies that compared people who slept seven to nine hours with those who regularly got less than six.

The results found that men with shorter sleep saw a noticeable drop in vaccine effectiveness. For women, the impact was less consistent, with researchers noting that hormone changes may play a role in how the immune system responds.

Anxiety

Dr. Peacock also pointed out that poor sleep and anxiety often feed into each other, creating a cycle that’s hard to break.

Lack of sleep can raise anxiety levels, and anxiety itself can keep you from being able to fall asleep in the first place, leading to even more restlessness.

She explained: "Unfortunately, one can exacerbate the other. Anxiety can have a negative effect on your body's ability to fall asleep, as your brain is in "fight or flight" mode, thinking of all the potential outcomes for whatever is causing the anxiety."

"Furthermore, anticipatory anxiety and specific anxiety about sleep can lead to sleep disturbance and insomnia, which then creates a feedback loop that can make both conditions worsen."

"It can cause us to have a reduced capacity for remaining positive when faced with emotionally challenging events,' says Dr Sue. 'You might also feel less able to enjoy positive experiences."

Menstrual irregularities can also be an issue Ekaterina Goncharova / Getty Stock

Menstrual Irregularities

Sleep deprivation doesn’t just affect mood and energy. According to Dr. Katharina Lederle, a sleep and body clock specialist, not getting enough rest can also disrupt menstrual health.

She explained: "The level of thyroid-stimulating hormone (TSH) increases during sleep deprivation, and in healthy young women in their follicular phase, is associated with a significant increase in TSH level."

"High levels of TSH causes menstrual irregularities, anovulation (when an egg isn't released), amenorrhea (when you don't get periods) and recurrent miscarriages."

Beyond all these health concerns, skimping on sleep can also lead to weight gain and lower productivity throughout the day. So if you’ve been debating whether to stay up late or go to bed, your health may thank you for choosing the pillow.