Skip to main content

Sleep Stages#

Sleep cycles are the progression through various stages of sleep, from light to deep sleep and REM (Rapid Eye Movement) sleep, occurring in a repeated pattern throughout the night. Flowtime tracks your sleep across the following stages:

  • Awake: Periods when you are awake during the night.
  • REM: A stage characterized by rapid eye movements, vivid dreams, and increased brain activity.
  • N1 (Stage 1): The lightest stage of non-rapid eye movement (NREM) sleep, a transition between wakefulness and sleep.
  • N2 (Stage 2): A deeper light sleep where body temperature drops and heart rate slows.
  • N3 (Stage 3): The deepest stage of NREM sleep, essential for physical restoration and recovery.

Every individual's sleep requirements are different, though the recommended amount is 7-9 hours for most adults. This is enough time for your body to go through four to five 90-minute sleep cycles. In general, you spend most of the night in N1 and N2 sleep.

How Does Flowtime Calculate Sleep Stages?#

Unlike other rings or wrist-worn trackers, the Flowtime Brain Tag utilizes advanced sensors to provide a detailed analysis of your sleep stages. The built-in EEG sensors, PPG, temperature, and motion sensors enable Flowtime to distinguish between the different sleep stages with high precision.

Main Features of Each Stage#

  1. Awake
    • Heart Rate: Variable, often higher than during sleep.
    • EEG: High-frequency brainwaves.
    • Temperature: Slight fluctuations.
    • Motion: Increased activity as you move around.
  2. N1 (Stage 1)
    • Heart Rate: Begins to slow down.
    • EEG: Low-amplitude, mixed-frequency waves; slow eye movements.
    • Temperature: Starts to drop.
  3. N2 (Stage 2)
    • Heart Rate: Continues to slow down.
    • EEG: Sleep spindles and K-complexes; no eye movements.
  4. N3 (Stage 3)
    • Heart Rate: Slow and steady.
    • EEG: High-amplitude, low-frequency delta waves.
    • Temperature: Skin temperature is at its highest
    • Motion: Very minimal; body is in a state of deep rest.
  5. REM (Rapid Eye Movement)
    • Heart Rate: Increased and variable.
    • EEG: Similar to wakefulness, with low-amplitude, mixed-frequency waves.
    • Motion: Rapid eye movements, minimal muscle activity.

Advanced Tracking with Flowtime#

Flowtime’s ability to track brainwaves using EEG sensors allows it to accurately differentiate between N1 and N2 stages, which are often combined as light sleep in other trackers. The PPG sensor monitors heart rate, while the temperature sensor keeps track of skin temperature fluctuations, and the motion sensor captures physical activity.

By leveraging this array of advanced sensors, Flowtime provides a comprehensive and precise analysis of your sleep cycles, helping you understand and improve your sleep quality.