How to Stop Sleep Inertia (Brain Fog)

Sleep inertia, or in other words, the brain fog after waking up and grogginess you feel in the morning, is due to the brain functioning differently than normal during sleep, especially deep sleep. Brain fog occurs as the brain tries to replenish cerebral blood flow. Anything that brings the brain activity to normal may reduce sleep inertia and help you feel more refreshed in the morning.

If you are getting a healthy amount of sleep then sleep inertia will usually fade after a half hour or so, otherwise, it can last as long as 2 hours. SleepSpace addresses sleep inertia using auditory stimulation where the alarm sound gradually increases in volume over a 10 minute period. This helps you get extra sleep when you need it and prevents that jolt feeling when you wake up. In other words, the SleepSpace Alarm Clock, eases your body awake.

Various scientific experiment have demonstrated that:

• Waking up is a gradual process and by awakening gradually you can counteract this negative perception of brain fog.

• The adverse effects of brain fog on reaction time can be totally abolished by a moderately intense continuous noise.

• Countermeasures to brain fog including physical or mental exercise, external noise, bright light, caffeine, and splashing water on your face.

• Bright light reduces brain fog after napping.

For an in-depth understanding of sleep inertia check out an interview Dr. Daniel Gartenberg gave to Quartz entitled, “Brain fog explains why you feel so groggy when you wake up”.


Ferraro & De Gennaro, 2000. The sleep inertia phenomenon during the sleep-wake
transition: theoretical and operational issues. Aviat Space Environ Med 71. pg. 843-848.

Kuboyama, T., Hori, A., Sato, T., Mikami, T., Yamaki, T., & Ueda, S. (1997). Changes in cerebral blood flow velocity in healthy young men during overnight sleep and while awake. Electroencephalography and Clinical Neurophysiology 102, 125-131.

Tassi, P & Muet, A. 2000. Sleep Inertia. Sleep Medicine Reviews, 4, 4, 341-353.

Tassi P, Nicolas A, Dewasmes G et al (1992). Effects of noise on sleep inertia as a function of circadian placement of a one-hour nap. Percept Motor Skills, 75: 291-302.

Hajak, G., Klingelhofer, J., Schulz-Varszegi, M., Matzander, G., Sander, D., Conrad, B., & Ruther, E (1994). Relationship between cerebral blood flow velocities and cerebral electrical activity in sleep. Sleep 17, pg. 11-19.

Ferraro & De Gennaro. (2000). The sleep inertia phenomenon during the sleep-wake
transition: theoretical and operational issues. Aviat Space Environ Med 71. pg. 843-848.

Hayashi, M., Masuda, A., & Hori, T. (2003). The alerting effects of caffeine, bright light and face washing after a short daytime nap. Clinical Neurophysiology 114, 2268-2278.

Baulk, S., Reyner, L., & Horne, J. (2001) Driver sleepiness-evaluation of reaction time measurement as a secondary task. Sleep, 24, 695-698.

Rupp, T., Arnedt, T., Acebo, C., & Carskadon, M. (2004). Performance on a dual driving simulation and subtraction task following sleep restriction. Perceptual and Motor Skills, 99, 739-753.