• The effects of sleep deprivation

    May 2008

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    Recent research outlines a connection between sleep and emotional stability. In the October 23, 2007, edition of Current Biology, researchers showed that when exposed to disturbing images, the part of the brain that controls emotional responses, the amygdala, was much more active in people who had missed a night’s sleep than in the control group who slept a normal amount.

    Sleep deprivation may contribute to depression and other psychiatric problems. 

    Although sleep deprivation is known to impair many human functions, including immune regulation, metabolic control, motor-functions, learning processes and memory processes, there has been little research on how sleep deprivation can affect the emotional brain-state.

    In this study, the researchers divided 26 undergraduate college students into two groups. One group stayed awake for two days and one night, about 35 hours. The control group slept normally. At the end of the second day, both groups were shown 100 disturbing images while undergoing brain scanning.

    When the brain activity in the amygdala was compared, the researchers found the sleep-deprived group showed 60 percent more reactivity in the emotional center of the brain. This represents the first set of experiments that demonstrate that when sleep deprived, even the brains of healthy people mimic certain pathological psychiatric patterns. The relationship outlined provides insights between sleep deprivation and mood.

    Previously, researchers believed sleep disorders were a result of psychiatric problems, but this study casts doubt on that assumption. The researchers believe this study could mean there is a close relationship between sleep deprivation and psychiatric problems like depression or posttraumatic stress disorder. Sleep deprivation may contribute to depression and other psychiatric problems, rather than depression causing sleep disorders.

    The right amount of sleep

    In a 2002 Sleep in America poll, Americans averaged 6.9 hours of sleep on weeknights and 7.5 hours of sleep on weekends. Most adults need about seven to eight hours of sleep per day, but sleep needs are individual. Researchers typically recommend young children (ages 3-4) get 11 to 13 hours of sleep, while school-aged children up to age 12 need 10 to 11 hours of sleep. Teenagers usually need at least nine hours of sleep.

    Sleep helps humans thrive by contributing to a healthy immune system, helping to balance our appetites and repair muscles. Since there is no magic number of how many hours of sleep are best, it is important to pay attention to how you feel. After a proper night’s sleep you should wake up feeling refreshed and alert without a need for stimulants or naps.

    Research has shown that sleeping too little can inhibit your productivity and ability to remember and consolidate information (learn). Short sleep duration is shown to lead to impaired vigilance and is thus linked with an increased risk of motor vehicle accidents. The National Highway Traffic Safety Administration estimates that at least 100,000 police-reported crashes (or 1.5 percent) are caused by drowsy drivers each year. Additionally, short sleep duration is linked with psychiatric conditions, increased risk of diabetes and heart problems, increase in body mass index, and a decreased ability to pay attention and remember new information.

    Alternatively, some research has also shown that sleeping too much can have negative effects. Long sleep durations (nine hours or more) have been associated with increased morbidity(illness, accidents) and mortality (death). Low socioeconomic status and depression are significantly associated with longer sleep duration. However, not enough research has been conducted to draw a strong link between sleeping more than nine hours and health problems.

    Tips for a good night’s sleep

    Experts recommend a few tips to aid in sleeping well.

    • During the day, remove caffeine from your diet. If you still need a caffeinated beverage to start your day, have it early and avoid all caffeine at least four to six hours before bedtime.
    • Try to exercise regularly; it has been show to play a key role in sleep.
    • Avoid napping during the day, and if you do be sure to keep it short (15-20 minutes).
    • In the evenings, avoid alcohol as a sleep aid; it can cause disturbances in sleep resulting in less restful sleep.
    • Try to relax before bedtime. It is beneficial to leave stress from the day behind before bedtime.
    • Avoid nicotine before bed; it puts a stimulant in your bloodstream that can keep you awake at night.
    • Avoid large meals right before bedtime; a full stomach can keep you awake. Some foods have been shown to aid in sleep including milk which contains tryptophan, a sleep-promoting substance. Other foods that may help promote sleep include tuna, halibut, pumpkin, artichokes, avocados, almonds, eggs, bok choy, peaches, walnuts, apricots, oats, asparagus, potatoes, buckwheat and bananas.
    • When it is bedtime, keep the bedroom quiet (no TV), dark and at a comfortable temperature. The ideal room temperature is between 68 and 72 degrees Fahrenheit. To prevent sleep disruption, try to avoid having your bedroom colder than 54 degrees or warmer than 75 degrees.
    • Having a pet sleep in your bed can also be disruptive to sleep due to allergies or pet movements. If this is a problem, consider having your pet sleep on the floor.
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  • Related resources

    For more information, see:

    Sleep Disorders Services UK HealthCare

  • UK Healthcare resources

    For more information, or to make an appointment with a UK HealthCare physician, please call UK Health Connection at 1-800-333-8874. 

Page last updated: 8/7/2015 1:30:14 PM
  • What the news means for you

    Mood-sleep deprivation link warrants further study

    Barbara Phillips, MD, MSPH
    Critical Care & Pulmonology

    Wright, Heather, MDAlthough this study is hypothesis-generating and interesting, we need more studies to determine if the relationship between mood and sleep deprivation truly exists.

    This study included young people who were deliberately sleep deprived. We don’t know how they were sleep deprived, which could have an effect. This was a very small study and with so many variables that can affect emotional response, more research will be needed to draw any conclusions.

    “We need more studies to determine if the relationship between mood and sleep deprivation truly exists.” 

    Sleep deprivation versus insomnia

    Sleep deprivation is very different from insomnia. Insomnia is characterized by difficulty falling asleep, difficulty staying asleep, or waking up too early; whereas sleep deprivation is just not allowing enough time to sleep the appropriate amount.

    The single parent who works all day, comes home and does a million chores, falls into bed at midnight, sleeps like a log for six hours and wakes up the next morning tired is sleep deprived. The woman who goes to bed at 10 p.m. but lies awake until 1 a.m. worrying about not getting enough sleep has insomnia.

    The main difference is the opportunity to sleep. Insomnia is often due to a mood disturbance but can sometimes be due to medical conditions including sleep apnea (cessation of breathing during sleep). We do not have nearly as much evidence that insomnia is harmful as we do that sleep deprivation is harmful.

    Influences of sleep

    Exercise has been shown to influence sleep. Exercise in varying amounts for all people has been shown to help people fall asleep better, make sleep more continuous and produce more deep restorative sleep. Exercise is the single most valuable non-drug.

    “When sleep deprived, we experience impaired mood, reduced vigilance, deterioration of memory and an increased risk of automobile accidents.” 

    Diet has also been shown to influence sleep, although we don’t know as much about diet and sleep as we do exercise and sleep. People with insomnia may have more effects from caffeine than those without insomnia. If you do have insomnia, I recommend avoiding caffeine. For people who are sleep deprived, caffeine has been shown to be a powerful and effective alerting agent and is an effective short-term countermeasure for sleep deprivation. In a situation where sleep loss is unavoidable, caffeine can literally be life-saving, particularly if you are going to be driving. However, it is important to remember that in the long run, nothing substitutes for sleep.

    Sleeping in a cool room on a comfortable mattress with no distractions (such as a TV) may also aid in helping you establish consistent sleep.

    Stages of sleep

    Sleep has two main parts: rapid-eye movement (REM) sleep and non-REM sleep. REM and non-REM sleep differ from each other in several aspects. REM sleep is best characterized as an active brain in a quiet body. Alternatively, non-REM (NREM) is a quiet brain in an active body.

    When you first fall asleep you enter the NREM stages of sleep. NREM is composed of separate stages and will last about 75 percent of the night.

    • Stage one is a light sleep.
    • Stage two is the onset of sleep where the body temperature will drop and breathing and heart rate are regular.
    • Stage three (slow wave sleep or delta sleep) is the deepest and perhaps most restorative sleep. In this stage, blood pressure drops, breathing becomes slower, hormones are released, muscles relax and blood supply to muscles increases. Tissue growth and repair also occurs during these stages.

    REM sleep generally first occurs about 90 minutes after falling asleep and recurs approximately every 90 minutes. During REM sleep the eyes dart back and forth and dreams occur. The body becomes immobile and relaxed because of an upper-motor neuron paralysis; this is thought to prevent us from acting out our dreams.

    Effects of sleep deprivation

    Scientists do not know the exact function of sleep, but we do know about some of the effects when humans experience sleep deprivation. When sleep deprived, we experience impaired mood, reduced vigilance, deterioration of memory and an increased risk of automobile accidents.  

    Dr. Phillips is director of the UK Good Samaritan Sleep Center and a professor of medicine at UK College of Medicine. She is a member of the board of the National Sleep Foundation and chair of the Sleep Institute of the American College of Chest Physicians.

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