You're likely not getting deep sleep due to poor sleep habits (inconsistent schedule, screens before bed), lifestyle factors (caffeine, alcohol, stress, lack of exercise), or underlying issues like sleep apnea, insomnia, anxiety, or certain medications, all of which disrupt your natural sleep cycles and prevent restorative rest. Addressing these controllable factors with good sleep hygiene is key, but persistent problems may require medical attention.
Low levels of melatonin, magnesium, vitamin D, or testosterone may reduce sleep quality. Elevated cortisol levels, poor glucose control, or thyroid issues can disrupt your sleep, shifting you from deep sleep to light, fragmented sleep.
11 tips to get more deep sleep and REM sleep at night
The negative effects from lack of REM sleep are serious: Without this critical sleep stage, your immune system could be weakened, you may experience pain more deeply, and the growth of new healthy cells and tissue in the body might be blocked.
You're likely not getting enough deep sleep due to stress, inconsistent sleep schedules, caffeine/alcohol, poor sleep hygiene (light/noise), certain medications, or underlying conditions like sleep apnea or anxiety, which fragment sleep, even if you're in bed for hours. Factors like aging, diet, and mental health also play roles in disrupting the restorative stages of sleep, preventing you from getting sufficient deep rest.
Here are seven common signs that you may not be getting enough deep sleep:
Melatonin, a hormone your body makes to help with your sleep cycle. It can also be found naturally in some foods. Good sources: tart cherries like Montmorency cherries, unsweetened tart cherry juice, eggs, milk, pistachios and almonds. Potassium and magnesium, nutrients that help promote muscle relaxation.
The Apple Watch's sleep stage algorithm was tested in a study of 166 people who wore both an Apple Watch and polysomnography equipment. Apple Watch was about 62% accurate in detecting deep sleep, confusing it for core sleep 38% of the time. This means your Apple Watch is likely to underestimate deep sleep.
If you've ever woken up feeling groggy and unrested after what should have been a good night's sleep, it's possible the culprit was a lack of deep sleep. Later that day, you may have had trouble focusing on tasks and felt irritable. Most everyone has experienced this at some point.
Vitamin D helps control the sleep-wake cycle.
One way or another, we know that vitamin D is involved in parts of the brain that regulate sleep timing — including hormones that control the sleep-wake cycle. “For example, vitamin D seems to affect how much melatonin is made in the body.
The koala is famous for sleeping around 20-22 hours a day, which is about 90% of the day, due to their low-energy diet of eucalyptus leaves that requires extensive digestion. Other extremely sleepy animals include the sloth (up to 20 hours) and the brown bat (around 20 hours), with some snakes like the ball python also sleeping up to 23 hours daily.
Factors that may cause a lack of deep sleep include:
Quick fixes to improve deep sleep:
The 3-2-1 bedtime method is a simple sleep hygiene strategy: stop eating 3 hours before bed, stop working 2 hours before bed, and stop using screens (phones, tablets, TVs) 1 hour before sleep, helping your body transition to rest by reducing stimulants and digestive load for better sleep quality. A more detailed version adds 10 hours (no caffeine) and 0 (no snoozing) for a 10-3-2-1-0 rule.
A lack of deep sleep can be caused by not getting enough sleep overall, drinking alcohol, pre-bed caffeine, stress, health conditions like depression and Alzheimer's disease, and sleep disorders like insomnia and sleep apnea. We also get less deep sleep as we age.
Cardiologists view the Apple Watch as a useful wellness tool for general heart awareness and detecting potential issues like atrial fibrillation (AFib), but not as a replacement for clinical devices, stressing it can't diagnose heart attacks or provide full diagnostic ECGs. They appreciate its ability to prompt users to seek care for irregularities, but caution against over-reliance due to risks of false positives, movement interference, and its single-lead limitation compared to 12-lead ECGs, emphasizing that symptoms always require a doctor's evaluation.
Some smartwatches use heart rate sensors to monitor your heart rate reading. Your heart rate lowers while sleeping also varies when you reach the different stages in the sleep cycle. So, this data change helps the watch track and monitor your sleep cycle closely.
Gamaldo recommends warm milk, chamomile tea and tart cherry juice for patients with sleep trouble. Though there isn't much scientific proof that any of these nighttime drinks work to improve your slumber, there's no harm in trying them, Gamaldo says.
Symptoms
Some people may naturally get more or less, and that's okay. Children and teenagers tend to have more deep sleep, while as you age, the amount of deep sleep may decrease. The key is to ensure you get enough quality sleep overall, as this will naturally include the necessary deep sleep cycles.
What the Sleep Doctors Say
Those with Alzheimer's were more likely to have delayed REM sleep, and they also tended to have higher levels of the two toxic proteins, amyloid and tau, found in people with the condition.