Sleep Time
Ensuring adequate sleep is one of the most important factors for both physical and mental health. The National Sleep Foundation recommends that adults aim for 6–10 hours of sleep each night. However, research shows that people vary widely: some are “habitual long sleepers” (around 10 hours per night), while others function normally as “habitual short sleepers” (under 6 hours).
This means sleep duration alone is not the only measure of sleep quality. If you regularly sleep less than the recommended standard but wake feeling refreshed, this is not considered insomnia. Similarly, simply extending sleep time does not necessarily improve recovery, and staying in bed too long may actually reduce sleep quality.
Sleep is structured into cycles of non-REM sleep (light and deep stages) and REM sleep. Each cycle lasts about 90–100 minutes, and a typical night includes 4–6 full cycles. The pattern of a cycle usually flows as wake → light sleep → deep sleep → light sleep → REM. Importantly, cycles are not identical: in the later part of the night, REM phases grow longer while deep sleep becomes shorter, ensuring balance between physical recovery and cognitive processing.
Deep Sleep
Deep sleep, also called slow-wave sleep, is when brain activity slows significantly, breathing becomes more regular, and blood pressure drops. This is the most restorative stage of sleep. If you are awakened during deep sleep, you may feel grogginess, dizziness, or restlessness.
During this stage, the brain is able to rest fully, fatigue is cleared, and emotional stability is reinforced. Deep sleep plays a vital role in restoring energy, stabilizing mood, and balancing mental health. In general, the longer your deep sleep duration, the higher your sleep quality. However, long-term consistently high proportions of deep sleep may indicate certain health conditions, and professional medical advice is recommended in such cases.
To improve deep sleep, follow the recommendations of the American College of Physicians (ACP), which suggests cognitive and behavioral therapy as the first-line treatment for insomnia. Clinical studies also show that chronic insomniacs often suffer from poor sleep habits. Improvements may include:
- Psychological factors: reducing excitement, anxiety, and depression that increase light sleep and reduce deep sleep.
- Physiological factors: managing fatigue, pain, or illness-related discomforts that disturb deeper sleep.
- Environmental factors: optimizing your bedroom for quietness, darkness, and comfort, with appropriate bedding and pillows.
- Rhythms of life: correcting irregular sleep schedules, shift work, or jet lag that disrupt your circadian rhythm.
- Diet: avoiding caffeine, nicotine, alcohol, and heavy meals close to bedtime.
- Exercise: engaging in moderate physical activity during the day can increase deep sleep, but avoid strenuous workouts right before bed, which may raise body temperature and delay sleep onset.
Light Sleep
Light sleep is the stage where brain activity slows, breathing and heart rate become more steady, and you enter rest but remain easily awakened. Light sleep is essential — waking up briefly is a normal protective mechanism — but when it makes up too much of the night, you may wake feeling unrefreshed and fatigued.
Excessive light sleep often results from the same factors that reduce deep sleep. Following the same improvement strategies — reducing stress, correcting irregular schedules, improving sleep environments, limiting stimulants, and balancing exercise — can help increase the share of restorative stages in your sleep cycle.
REM Sleep
REM (Rapid Eye Movement) sleep is characterized by rapid eye movements beneath the eyelids. Most people awakened during this stage report dreaming. Muscles remain in a state of paralysis as a protective mechanism, preventing us from acting out our dreams — which explains why dreams often feel as though you cannot move or shout.
REM sleep is critical for mental health, memory processing, stress relief, and creativity. Research shows that when people are deprived of REM sleep, they quickly develop irritability, tension, and fatigue. A high proportion of REM may appear as frequent dream recall. This is not always negative, but if the REM ratio is consistently abnormal and paired with anxiety or mood issues, professional consultation is recommended.
To support healthy REM sleep:
- Daily rhythm: Later sleep cycles contain longer REM periods. Going to bed earlier and maintaining regular schedules helps normalize this.
- Mental health: Avoid excessive stress or anxiety, which can shorten REM phases.
- Diet and stimulants: Limit alcohol, caffeine, nicotine, and certain medications that interfere with REM sleep.
Night Awakenings
Awakenings during the night vary from very brief micro-arousals to longer interruptions. Most people experience up to two awakenings per night, with total wake time under 10% of the night. More frequent awakenings may point to insomnia or disrupted sleep cycles.
If you frequently wake and struggle to fall back asleep, accompanied by fatigue, anxiety, or irritability, consider these strategies:
- Keep a strictly regular sleep-wake routine, regardless of how well you slept the night before.
- Expose yourself to daylight in the morning, limit naps, and avoid long daytime sleep.
- Avoid stimulating activities before bed (TV, phones, problem-solving).
- If you wake, remain calm and avoid checking the clock repeatedly.
- Maintain a comfortable sleep environment with the right temperature, noise control, and lighting.
- Engage in moderate exercise during the day to promote nighttime sleep, but avoid strenuous workouts late in the evening.
Napping
Naps can help restore alertness and energy, especially if nighttime sleep was insufficient. The ideal nap is 15–30 minutes before 1:00 p.m.. Longer naps, especially those exceeding 45 minutes, may push you into deep sleep and result in grogginess, dizziness, or nausea upon waking.
Napping too late in the day can interfere with nighttime sleep by disrupting body temperature rhythms. The best time for naps aligns with the natural midday dip in body temperature, which increases sleepiness.
*A single sleep of less than 1 hour is counted as sporadic naps.
How NAVA Helps
The NAVA Ring App tracks sleep stages (light, deep, and REM), total duration, and nighttime awakenings. It also measures recovery indicators such as HRV, heart rate, and body temperature changes. With this data, NAVA provides personalized AI-driven recommendations, helping you optimize your sleep quality, correct imbalances, and wake feeling refreshed.
