Excessive daytime sleepiness
refers to the inability to stay
alert during the major awake
period of the day, resulting
in you falling asleep at
inappropriate times. When
sleepiness interferes with
daily routines and activities,
or reduces your ability to
function, it is considered
This is a prevalent condition. In
Singapore, the prevalence of
excessive daytime sleepiness has
been reported to be 9 percent
(Ng TP et al, Sleep Medicine 2005).
Causes of excessive daytime sleepiness include the following. It is commonly caused by more than one of these causes.
1. Inadequate sleep
The amount of sleep needed each
night varies amongst different people.
Most need seven to eight hours of
uninterrupted sleep to maintain
alertness the following day. A habitual
sleep period of less than four to five
hours daily is generally insufficient to
maintain normal daytime alertness
and is likely to cause excessive daytime
If you do not get enough sleep
even on a single night, a ’sleep debt’
begins to build and increases until
sufficient sleep is obtained. Excessive
daytime sleepiness occurs as the debt
accumulates. If you do not get enough
sleep during the work week, you may
tend to sleep longer on the weekends
or days off to reduce your sleep debt.
2. Sleep disorders
Sleep disorders such as obstructive sleep apnoea, narcolepsy, restless legs syndrome and insomnia may cause excessive daytime sleepiness.
- Obstructive sleep apnoea is a potentially serious disorder in which your breathing is interrupted during sleep. This causes you to awaken many times during the night and experience excessive daytime sleepiness.
- Narcolepsy will cause excessive daytime sleepiness during the day, even after getting sufficient sleep at night. You may fall asleep at inappropriate times and places.
- Restless legs syndrome causes a person to experience unpleasant sensations in the legs. These sensations frequently occur in the evening, making it difficult for you to fall asleep, leading to excessive daytime sleepiness.
- Periodic limb movement disorder is a sleep disorder where there is
involuntary limb movement during
sleep, leading to excessive daytime
sleepiness, difficulty falling asleep
at night or difficulty staying asleep
throughout the night
- Insomnia is the perception of poorquality sleep due to difficulty falling asleep, waking up during the night with difficulty returning to sleep or waking up too early in the morning.
Some medications may disrupt sleep and cause sleepiness. Examples include sedating antihistamines, sedatives, antidepressants and seizure medications.
Alcohol is sedating and can, even in small amounts, make a person more sleepy and at greater risk of car crashes and performance problems.
Caffeine in coffee, tea, soft drinks or medications makes it harder for many people to fall asleep and stay asleep. Caffeine stays in the body for about three to seven hours, so even when taken earlier in the day, it may cause problems in falling asleep at night.
Nicotine from cigarettes is also a stimulant and makes it harder to fall asleep and stay asleep.
7. Medical conditions
Chronic medical conditions such as asthma, heart failure, depression, rheumatoid arthritis or any other chronically painful disorder may also disrupt sleep and lead to excessive daytime sleepiness. Excessive daytime sleepiness may also occur following head injury and rarely, due to brain tumour.
8. Sleep-wake cycle disturbance (such as shift work)
Most shift workers get less sleep over 24 hours as compared to day workers. The human sleep-wake system is designed to facilitate the body and mind for sleep at night and wakefulness during the day. These natural rhythms make it difficult to sleep during daylight hours and to stay awake during the night hours, even in well-rested individuals.
Sleep loss is greatest for night shift workers, those who work early morning shifts and female shift workers with children at home. Shift workers who try to sleep during the day are frequently interrupted by noise, light, the telephone, family members and other distractions.
Identifying the cause(s) of excessive daytime sleepiness is the key to its management. Treatment is directed towards the specific underlying cause. Obstructive sleep apnoea is generally treated with continuous positive airway pressure (CPAP).
In general, medications do not help problem sleepiness and some medications may make it worse. Medications may be prescribed for patients in certain situations.
Short-term use of sleeping pills has been shown to be helpful in patients diagnosed with acute insomnia. Long-term use of sleep medication is recommended only for treatment of specific sleep disorders. Stimulants to maintain alertness are used in the treatment of narcolepsy.
Get enough sleep
Many people do not set aside
enough time for sleep on a
regular basis. A first step may be
to evaluate your daily activities
and sleep-wake patterns to
determine how much sleep is
obtained. If you are getting less
than 8 hours of sleep, more sleep
may be needed.
A good approach is to gradually
move to an earlier bedtime.
For example, if an extra hour of
sleep is needed, try going to bed
15 minutes earlier each night for
four nights, then keep to the last
bedtime. This method will
increase the amount of time in
bed without causing a sudden
change in schedule.
Avoid beverages containing
caffeine (coffee, tea and some
soft drinks). Caffeine can help to
reduce sleepiness and increase
alertness but the effect is
temporary. It can cause problem
sleepiness to become worse by
While alcohol may shorten the time
it takes to fall asleep, it can disrupt
sleep later in the night, leading to
poor quality sleep and adding to
problem sleepiness. Chronic use of
larger quantities of alcohol can also
lead to alcohol dependency.