Sleep affects everything from physical and mental performance to mood and weight control. But for something so key to your health and wellness, exactly how sleep works is still a mystery to many of us. Here’s what you need to know if getting more sleep or better sleep is your goal.

You’re not alone

Sixty million Americans persistently suffer from sleep deprivation. And 70% of U.S. adults experience enough daily stress to the point it disrupts their nightly sleep. So what’s going on?

It’s all about hormones

The body’s alternating cycle of sleeping and waking is directly related to the levels of two key hormones: melatonin and cortisol. Understanding how the levels of these two hormones fluctuate during the day, and how they relate to each other, is important for determining why you’re not sleeping well.

How melatonin levels can disrupt your sleep cycle

Your melatonin level directly impacts your sleep cycle because it induces and maintains normal sleep. Melatonin regulates the body’s internal biological clock. Melatonin is produced in the pineal gland, a pea-sized gland in the brain. During the day, the pineal gland is inactive, but when the sun goes down and it starts getting dark, the pineal is activated and begins to produce melatonin. Your melatonin level typically peaks around bedtime, it stays elevated throughout the night, and then it falls back to daytime levels in the morning when its production is “shut off” by daylight.

The feedback between your body and your environment is the primary way your body knows when it should be asleep or awake. So if melatonin does not increase properly at night or its production is disrupted by light or other factors, then you can experience difficulty falling asleep, or you wake up frequently during the night, and you suffer from fatigue and other symptoms of sleep deprivation during the day.

How cortisol levels can disrupt your sleep cycle

Cortisol is a stress hormone made in the adrenal glands. Cortisol has many roles in the body, but it has a special relationship to sleep, because it balances melatonin. Although your cortisol level follows a cycle that is opposite to melatonin, it’s also responsible for signaling your body to be awake and responsive. Normally, your cortisol level peaks 30-60 minutes after you wake up and then it fluctuates throughout the day. Your cortisol level should be lowest at night, when melatonin level is high. When you have a healthy level of cortisol, and it follows the typical fluctuation pattern, it helps wake you up in the morning, regulates energy and hunger, and modulates your normal response to physical and emotional stress throughout the day.

But your cortisol level can become unbalanced from chronic stress related to emotions, lifestyle, diet, health issues, overtraining, and other causes. There are abnormal patterns, but a frequent abnormal pattern is high cortisol in the evening, which results in wakefulness instead of sleepiness. In this case, you experience difficulty falling asleep and staying asleep, plus you might crave food and feel “tired but wired.”

Is it possible you have an issue with melatonin? Ask yourself these questions.

  • Do you have difficulty falling asleep at night?
  • Do you wake up frequently during the night?
  • Do you wake up too early in the morning?
  • Are you experiencing fatigue?
  • Are you feeling poorly rested?
  • Do you experience daytime tiredness or sleepiness?

Is it possible you have an issue with cortisol? Ask yourself these questions.

  • Do you have disrupted sleep?
  • Do you think your sleep is poor quality?
  • Do you frequently feel “tired but wired”?
  • Are you frequently anxious or stressed out?
  • Are you easily irritated?
  • Are you getting sick more frequently?
  • Do you have unexplained aches and pains?
  • Do you have digestive issues?
  • Do you have food cravings?
  • Are you gaining too much weight?