About Sleep

Short Term Effects of Poor Sleep

In the short term, poor sleep causes increased blood pressure, snacking on fatty foods, insulin resistance, decrease in various cognitive functions, ability to learn[2], weakened immune system, and even a decrease in your sense of humor[3]. One study found that even a 1-hour difference in sleep can dramatically affect the body, where heart attacks increased during daylight savings time when an hour of sleep was lost.

Furthermore, acute sleep deprivation is equally as dangerous as drunk driving.

Long Term Effects

In the long-term, unhealthy sleep is linked to decreased life span, increased obesity, cardiovascular disease, Type II Diabetes, illnesses, like the common cold[4], and neurological disorders[5].

While people are more likely to live longer if they sleep ~7-8 hours a night [6][7], it is difficult to determine whether sleep is the cause because other factors may influence this finding. However, the short-term effects of sleep deprivation on the cardiovascular, digestive, immune, and neurological systems, in conjunction with the long-term correlations between health and sleep, suggests that sleep is crucially important to your general well being.

Proactive Sleep can help you understand and characterize your unique sleep patterns so you can identify possible sleep problems and figure out how to address these problems.

Body Cycles

The human body has cyclical ebbs and flows much like the ocean tide. As a result, there are better and worse times to wake up, fall asleep, do work, take a nap, etc. Also like the tide, with the right information, these patterns can be predicted. This requires understanding sleep stages and the homeostatic and circadian components of our bodily cycles.

Sleep is Dynamic

Sleep is made of generally three stages:

  1. Light Sleep
  2. Deep Sleep
  3. REM sleep

These recur somewhat predictably in about one to two-hour intervals following the pattern:

light sleep → deep sleep →
light sleep → REM

The two major factors that affect sleep/wake patterns are the homeostatic and circadian components.

The Stages of Sleep

Deep sleep contrasts greatly with the brainwaves that occur in REM, light sleep, and waking life. During deep sleep, the frequency of brainwaves decreases, and the wavelength increases, as large swaths of neurons fire on and off in a long oscillating manner. Since this is very different from brainwaves that occur when you are awake, waking during deep sleep increases grogginess and disorientation.

Homeostatic Component

The Homeostatic Component is the accumulated pressure to fall asleep the longer that you are awake. When you are sleep deprived, the body compensates by the increased need to fall asleep and increased amount and intensity of deep sleep. Since deep sleep dissipates as sleep needs decrease, sleep cycles get gradually shorter if you sleep for a longer amount of time and are less sleep-deprived.

Circadian Component

The Circadian Component operates in a 24-hour cycle and affects various biological processes throughout the day, such as body temperature, blood pressure, and sleepiness. You may find it particularly difficult to wake up at about 2:00 am to 4:00 am and that you are usually drowsy after lunch, at around 2:00 pm to 4:00 pm [3][4][5]. This is due to the circadian component, which is usually at its lowest point during these times. Exposure to bright light in the morning is known to affect this aspect of the sleep/wake cycle.

Sleep Inertia

Sleep inertia, or in other words, the grogginess you feel upon waking up in the morning, is due to the brain functioning differently than normal during sleep, some claiming that it is largely due to lower cerebral blood flow[1][2]. Thus, anything that increases cerebral blood flow, such as brain activity may decrease sleep inertia and make you feel more refreshed in the morning [3]. These scientific experiments have demonstrated that:

Waking up is a gradual process[4].

  • The adverse effects of sleep inertia can be totally abolished by a moderately intense continuous noise[5].
  • Countermeasures to sleep inertia include physical or mental exercise, external noise, bright light, and caffeine [6].
  • Bright light reduces sleep inertia after napping[7].
  • Stimulating tasks (such as Proactive Games) may promote alertness when sleep deprived[8][9].


Scientific evidence has shown that napping can improve waking performance and alertness, even after a normal night of sleep. Additionally, it counteracts the decreased alertness experienced when sleep deprived [1].

There are general guidelines for napping that when followed, can optimize the effectiveness of a nap. For example, you should nap when the circadian component of sleep is low in order to reduce how long it takes you to fall asleep. Also, taking a nap that is longer than 30 minutes but less than 80 minutes increases the likelihood of awakening during deeper sleep, which can be counterproductive to your alertness and energy level [2]. Lastly, napping longer than 30 minutes or in the late afternoon can interfere with the following night of sleep [3].

Furthermore, different types of naps are appropriate for different circumstances. This includes taking 1) Replacement Naps when you are sleep deprived, 2) Appetitive Naps to improve performance, and 3) Prophylactic Naps in preparation of sleep deprivation.

Replacement Naps are taken to make up for previous sleep loss. These naps should be longer to ensure the restorative powers of a complete sleep cycle. For example, if you are sleep deprived and the homeostatic pressure to fall asleep is high, a longer nap of about 90 minutes may be appropriate. Sleeping for an entire sleep cycle confers the greater restorative benefits of sleep while also ensuring that you do not awaken in deep sleep.

On the other hand, if you are not sleep deprived shorter naps of less than about 30 minutes are advised. These are labeled Appetitive Naps. In a recent study, people who took less than 20-minute naps in the mid-afternoon experienced increased work performance and rated themselves as being less tired [4][5].

The best time to take a nap can also be influenced by how long you plan to be awake. If you know that you are going to stay awake for a long period of time, taking a nap prior to this period of sleep deprivation benefits performance[6]. These types of naps that are taken in advance of sustained wakefulness are known as Prophylactic Naps. Thus, it may be better to nap prior to sleep deprivation than during the period of sleep deprivation.

A future goal is to be able to predict which type of nap you should take so you feel more refreshed.


1) Cirelli C, Tononi G. Is sleep essential? PLoS Biology, 6:e216, 2008.

2) Huber, R., Ghilardi, M. F., Massimini, M., Ferrarelli, F., Riedner, B. A., Peterson, M. J., & Tononi, G. (2006). Arm immobilization causes cortical plastic changes and locally decreases sleep slow-wave activity. Nature Neuroscience, 9, 9 1169-1176.

3) Thomas, M, Sing, H, Belenky, G, Holcomb, H, Mayberg, H, Dannals, R, Wagner, Jr., H, Thorne, D, Popp, K, Rowland, L, Welsh, A, Balwinski, S, and Redmond, D (2000). Neural basis of alertness and cognitive performance impairments during sleepiness: Effects of 24 h of sleep deprivation on waking human regional brain activity. Journal of Sleep Research, 9, 335-352.

4) Diekema, D. J. (2009). Sleep and the common cold. Journal Watch Infectious Disease, 12, 2, 9.

5) Tononi, G. & Cirelli, C. (2005). Sleep function and synaptic homeostasis. Sleep Medicine Reviews, 1-14.

6) Kripke, D., Garfinkel, L., Winegard, D., Klauber, M., & Marler, M. (2002). Mortality associated with sleep duration and insomnia. Arch Gen Psychiatry, 69 131-136.

7) Wingard, D. & Berkman, L. Mortality Risk Associated with Sleeping Patterns Amoung Adults. Sleep, 6, 2, 102-107.

8) Kuboyama, T., Hori, A., Takayuki, S., 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.

9) Tassi, P., Bonnefond, A., Engasser, O., Hoeft, A., Eschenlauer, R., Muzet, A. (2006). EEG Spectral power and cognitive performance during sleep inertia: The effect of normal Sleep duration and partial sleep deprivation. Physiology & Behavior 87, 177.

10) Dinges, D. F., Orne, M. T., & Orne, E. C. (1985). Assessing performance upon abrupt awakening from naps during quasi-continuous operations. Behavior Research Methods, Instruments, & Computers, 17, 1, 37-45.

11) Takahashi, M., Fukuda, H., Arito, H. (1998). Brief naps during post-lunch rest: effects on Alertness, performance, and autonomic balance. Eur J Appl Physiol 78, 83-98.

12) Scheef, F., Shea, T., Hilton, M., and Shea, S. (2008). An endogenous circadian rhythm in sleep inertia results in greatest cognitive impairment upon awakening during the biological night. Journal of Biological Rhythms 23, 4, 353-361.