Daytime tiredness is a common health complaint made all the more frustrating when we have spent an entire night in bed. When sleep is not restful, the cause is usually correctable with lifestyle factors that allow for quality sleep, known as sleep hygiene, are improved. In other cases, constant daytime sleepiness or sudden periods of drowsiness can be a symptom of a sleep disorder.
Not Enough Sleep
The most common reason why we feel tired after a night's sleep is simply that we did not get enough sleep. Seven to nine hours of sleep is considered the norm for healthy sleep. The exact amount varies for individuals, as some actually do fine on five hours and a minority of adults require up to 10 hours a night. However, the norm of seven to nine hours of sleep should not be counted from the moment of lying down to the time the alarm goes off. After all, many people require at least 20 to 30 minutes to fall asleep once in bed, and many people have normal periods of alertness during the night too. Although functioning on less than five or six hours of sleep is possible for a few nights in a row, it is not sustainable as the result is consistent daytime tiredness, slower thinking, clumsier actions and grouchier moods.
Too Much Sleep
On the other hand, sleeping too much can also cause daytime tiredness and sluggishness. More than 10 hours of sleep a night for adults is considered excessive sleep and may be a symptom of depression. The National Sleep Foundation suggests that the relationship between sleep and depression is not always the case of causation, but actually a confluence of symptoms that increases the likelihood of one another. The upshot is that excessive sleep and depression respond to the same treatments, such as antidepressants and cognitive therapies.
Sleep Fragmentation
Sleep is not a single event that happens when we close our eyes. Rather, sleep consists of different stages that each performs different restorative functions for the body and mind. These stages can be broken up into light sleep, deep sleep and REM, also known as dreaming sleep. Sometimes, daytime tiredness is a symptom of multiple awakenings, resulting in fragmented sleep in which the brain is prevented from getting enough deep or REM sleep. In this case, sleep apnea may be the cause. This is a breathing related sleep disorder that can easily go unnoticed because these multiple awakenings cannot usually be remembered. This is especially true for those who sleep alone. The CDC notes that other common symptoms of sleep apnea are loud snoring and waking up gasping for breath. Sleep apnea can cause serious health risks, including a shortened lifespan, so seeing a sleep specialist is highly recommended if these symptoms are a constant complaint.
Narcolepsy
Narcolepsy is a sleep disorder that is marked by daytime sleepiness. Another unmistakable sign of narcolepsy is "irresistible sleepiness," or a sleep attack that happens suddenly. Other lesser-known symptoms of narcolepsy include strong emotional outbursts and muscle paralysis during the daytime that feels like the muscles going completely limp. Narcolepsy can also have symptoms of sleep apnea, so for this range of symptoms it is recommended to make an appointment with a sleep specialist. According to the National Institute of Neurological Disorders and Stroke, treatments include pharmaceuticals and education about sleep hygiene.
