Sleep Inertia: Why You Still Feel Tired After Sleeping and What to Do About It
Sleep Inertia: Why You Still Feel Tired After Sleeping and What to Do About It
Ever wake up feeling groggy, disoriented, and like your brain is still half-asleep? That heavy, sluggish sensation that lingers after you have opened your eyes is known as sleep inertia. While it is completely normal, it can be frustrating—especially when you need to be alert and productive first thing in the morning. The culprit? Sleep inertia.
Sleep inertia is the temporary state of impaired cognitive performance, reduced alertness, and a strong desire to go back to sleep that occurs immediately after waking. It can last from a few minutes up to 30–60 minutes, and in some cases even longer. During this time, reaction times are slower, memory is less reliable, and judgment may be impaired—all of which can make early-morning tasks more challenging.[1] Several factors can contribute to the intensity and duration of sleep inertia:
• Waking During Deep Sleep: If your alarm interrupts you during slow-wave sleep (also known as deep sleep), you’re more likely to experience stronger sleep inertia. This phase of sleep is restorative but also the hardest to wake up from.[2]
• Sleep Deprivation: Not getting enough rest increases your chances of waking up in a deeper stage of sleep. Chronic sleep debt also intensifies grogginess upon waking.[3]
• Circadian Rhythms: Waking up at odds with your body’s internal clock—such as during the night or very early morning—can amplify sleep inertia. Night shift workers and frequent travelers often feel this effect more acutely.[4]
• Sleep Disorders: Conditions like sleep apnea or insomnia may disrupt normal sleep cycles, making deep sleep more fragmented and leading to more pronounced sleep inertia.[5]
The good news is there are ways to reduce the severity of sleep inertia and wake up feeling more refreshed:
1. Get Enough Sleep: Aim for 7–9 hours of quality sleep per night. Going to bed and waking up at the same time every day—even on weekends—helps stabilize your sleep cycles and reduces the chances of waking during deep sleep.[6]
2. Use Sleep Cycle Alarms: Apps or wearable devices that track your sleep stages can wake you during a lighter phase of sleep, making it easier to rise without grogginess.[7]
3. Expose Yourself to Natural Light: Natural sunlight helps reset your circadian rhythm and increases alertness. Try opening your blinds right away or stepping outside for a few minutes after waking.[8]
4. Hydrate First Thing: Dehydration can worsen fatigue. Drinking a glass of water soon after waking helps kickstart your metabolism and can reduce the feeling of sluggishness.[9]
5. Avoid Hitting Snooze: Though it is tempting, repeatedly snoozing your alarm disrupts your sleep cycles and can cause you to re-enter deep sleep, making it harder to wake up the next time.[10]
6. Try a Morning Routine with Movement: Light physical activity, such as stretching or a short walk, can help get your blood flowing and improve your mental clarity faster than staying in bed scrolling on your phone.[11]
Sleep inertia is a common but manageable part of the waking process. By paying attention to your sleep habits and making small adjustments to your routine, you can reduce grogginess and start your day feeling more energized and clear-headed. While it might not be possible to completely eliminate sleep inertia, understanding it gives you the power to work with your body—not against it—for smoother, more alert mornings.
*Be sure to speak with your doctor before making any changes to your lifestyle, diet, or exercise regime.
[1] Tassi, Patricia, and Alain Muzet. "Sleep inertia." Sleep Medicine Reviews, vol. 4, no. 4, 2000, pp. 341–353.
[2] Dinges, David F. "Are you awake? Cognitive performance and fatigue." Sleep, vol. 18, no. 10, 1995, pp. 123–125.
[3] Van Dongen, Hans P. A., et al. "The cumulative cost of additional wakefulness: Dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation." Sleep, vol. 26, no. 2, 2003, pp. 117–126.
[4] Jewett, Megan E., et al. "Time course of sleep inertia dissipation in human performance and alertness." Journal of Sleep Research, vol. 8, no. 1, 1999, pp. 1–8.
[5] Akerstedt, Torbjörn, and Mats Gillberg. "Subjective and objective sleepiness in the active individual." International Journal of Neuroscience, vol. 52, no. 1-2, 1990, pp. 29–37.
[6] Hirshkowitz, Max, et al. "National Sleep Foundation’s sleep time duration recommendations: methodology and results summary." Sleep Health, vol. 1, no. 1, 2015, pp. 40–43.
[7] Tonetti, Lorenzo, et al. "Circadian preference and the sleep–wake cycle: a questionnaire study." Chronobiology International, vol. 25, no. 2-3, 2008, pp. 196–207.
[8] Cajochen, Christian, et al. "High sensitivity of human melatonin, alertness, thermoregulation, and heart rate to short wavelength light." The Journal of Clinical Endocrinology & Metabolism, vol. 90, no. 3, 2005, pp. 1311–1316.
[9] Armstrong, Lawrence E., et al. "Mild dehydration affects mood in healthy young women." The Journal of Nutrition, vol. 142, no. 2, 2012, pp. 382–388.
[10] Trotti, Lynn Marie. "Waking up is the hardest thing I do all day: Sleep inertia and sleep drunkenness." Sleep Medicine Reviews, vol. 18, no. 6, 2014, pp. 537–541.
[11] Buman, Matthew P., et al. "Exercise as a treatment to enhance sleep." American Journal of Lifestyle Medicine, vol. 5, no. 6, 2011, pp. 518–528.