Why sleep matters: how lack of sleep affects your physical health

Did you know that even modest sleep loss can affect your blood sugar and metabolism? It’s true! When you consistently sleep fewer than seven hours a night, your body becomes less efficient at using insulin (that’s the hormone that regulates your blood sugar). Here’s the proof: in a 2023-2024 clinical trial, researchers had healthy women cut their sleep by about 1.5 hours every night for six weeks. The women developed significantly higher insulin levels and insulin resistance compared with when they were getting about eight hours of sleep each night. Based on the numbers, their bodies were sliding toward a pre-diabetic state after prolonged sleep deprivation, without any big weight gain.¹ That means the change was directly due to sleep loss as opposed to diet or other factors.

Sleep and weight are tightly connected. When you’re consistently sleep deprived, your body’s hunger signals get thrown off: ghrelin (the hormone that increases your appetite) goes up, while leptin (the hormone that signals fullness) goes down. This shift makes you feel hungrier and crave calorie-dense foods. Research has also shown that even after just one night of only 4-5 hours of sleep, subjects report a stronger desire for high-carb, high-sugar foods and tend to consume more calories the next day. Over time, this can add up.

Have you noticed you tend to get sick more often when you’re run down? It’s not a coincidence; it’s because your immune system recharges when you’re sleeping. Consistently skimping on your sleep can weaken your immune defenses and increase inflammation in your body.² Researchers have also found that losing roughly 1.5 hours of sleep each night triggered the production of more immune cells…but with a catch: these immune cells showed altered DNA expression and a pro-inflammatory profile, as if the body was under stress. Even after returning to a normal 8-hours-per-night sleep routine, some of these immune cell changes continued.²

Do you feel achy and sore when you haven’t slept well? It’s because insufficient sleep lowers your pain threshold and makes discomfort more intense. In a 2023 study using mice, researchers discovered that chronic sleep disruption led to changes in a specific brain neurotransmitter that increased pain sensitivity.³ By applying this to the human body, we can assume that sleep loss can indeed amplify pain. This can turn into a vicious cycle in which pain disrupts sleep, lack of sleep makes pain feel worse, and so on.

While this is far from an exhaustive list of the physical effects of lack of sleep, you can clearly see that poor sleep doesn’t just lead to you feeling tired – it can have real consequences for your body. The good news is that it can be improved by prioritizing better sleep. Here are three actions you can take immediately for better sleep and better overall health: