Good sleep isn’t just about how many hours you log
With technology at our fingertips, there’s an overwhelming amount of information floating around—especially in the health and wellness world. You hear buzzwords like “delta sleep,” and “circadian rhythm,” but what do they actually mean? Let’s dive into sleep (I wish).
What is sleep, really?
Sleep is the biological process that allows our body to rest and recover. There are key processes that the body undergoes when you’re asleep: conserving energy, self-repair, healing injuries, and brain maintenance. The amount of sleep can affect how you function, however, how much sleep a person needs varies due to age, sex, genetics, presence of illness or injury, stress. In addition, there are factors that affect your sleep quality or stages on a daily or overall basis, such as stress, hormones, and food intake and its quality. Finally, your circadian rhythm regulates your body’s natural sleep-wake cycle that repeats every 24 hours. It tells you if you’re feeling sleepy or awake based on your internal clock.
I’ve heard of sleep cycles, but what does each one do?
While sleeping, your brain goes through phases or patterns that provide different benefits. The stages divide between two categories: rapid eye movement (REM) and non-rapid eye movement (NREM). Within NREM, there are three stages, starting with stage 1, then stage 2 and stage 3. Next, the cycle transitions into REM sleep, with the overall cycle lasting between 90 to 120 minutes, repeating four to five times throughout the night.
Let’s go a little deeper.
Stage 1 of NREM is your lightest sleep that you transition into after falling asleep. This stage is the quickest, only lasting a few minutes before transiting into stage 2.
Stage 2 is light sleep as well, however, the brain spends longer time during this stage, accounting for 45% of time asleep. During this stage, the wave lengths begin to slow with some short bursts of activity. These bursts may be due to organizing memories or information.
Finally, the last stage of NREM is stage 3, which is known as “delta sleep”. Stage 3 is your deepest sleep accounting for 25% of your sleep time. The wavelengths are long and allow your body to heal injuries and improve your immune system. You may also see bursts of activity during this stage. Stage 3 leaves you feeling rested for your day, but if someone is awoken during stage 3, it may be difficult to fully arouse them. They may fall back asleep or have a sleep “hangover.”
Next, your body transitions from NREM to REM sleep. Typically, the first cycle of REM is your shortest, lasting about 10 minutes, however, each cycle after it continues to become longer. During this phase, there is vivid dreaming and heightened brain activity, where there is memory and information consolidation, improves cognitive function, and mood regulation. Your body is in a state of atonia, or temporary paralysis. The brain activity of being awake and during REM are very similar. REM sleep is about 25% of your sleep time. Understanding your sleep stages helps you make smarter choices around bedtime.
Good sleep isn’t just about how many hours you log—it’s about the rhythm of your sleep cycle. If you’re waking up tired, it might not be how long you’re sleeping, but how well you’re moving through these stages. Learning how sleep works can help you optimize your full sleep potential—and wake up truly refreshed.