Understanding Sleep Cycles

Our sleep is divided into several stages known as sleep cycles. Each cycle typically lasts around 90 minutes, cycling through stages of lighter sleep, deep (slow-wave) sleep, and REM (rapid eye movement) sleep. Over the course of a night, a healthy adult will go through four to six cycles, each critical for overall recovery and brain function.

The Stages of Sleep

• N1 (Light Sleep): This is the transition from wakefulness to sleep. Muscle activity slows, and you drift in and out of light dozing.
• N2 (Stable Sleep): Heart rate and breathing slow, and your body temperature drops. This stage makes up the majority of your nightly rest.
• N3 (Deep Sleep): Also called slow-wave or delta sleep. This is the most restorative stage, where tissue growth and repair occur.
• REM (Dreaming Sleep): Your brain becomes more active, and most vivid dreams happen here. It plays a significant role in memory consolidation and emotional health.

Why Sleep Cycles Matter

Each sleep cycle contributes to a different aspect of restoration—deep sleep helps heal your body, while REM sleep supports memory and learning. Waking up in the middle of a cycle can leave you groggy. Conversely, aligning your alarm with the lighter stages can help you feel more refreshed.