Sleepiness and tiredness are two feelings that we often refer to interchangeably. However, there is a difference. We all experience that sleepy feeling as night approaches. This is due to our biological clock that increases sleep hormones when it is time to rest. It correlates with a tired feeling which also tends to arise after a long day or with strenuous physical activity.
These two feelings correlate because our body needs rest at certain times within a 24 hour cycle (sleep) and particularly when overworked and needs to rejuvenate (tiredness). Sleeping should resolve these sensations. This means that we no longer feel sleepy after sufficient sleep. Similarly the tired feeling should also cease after sleeping for a suitable period of time.
Waking Up Feeling Tired or Sleepy
Although not every person is a ‘morning person, energy levels and alertness should be higher during the day. Tiredness and sleepiness sets in by the later parts of the day, usually by late afternoon or early evening. It is therefore considered to be abnormal to feel sleepy in the morning, after a sufficiently long sleep.
There are instances where we all wake up feeling tired or sleepy. It occurs after a late night, unusually strenuous activity or an uneasy and disturbed sleep for any reason. The causes of morning fatigue, which is tiredness after waking up, may not always be the same as the causes of a sleepy feeling after waking up. Some of these causes may however overlap.
Adequate sleep is an essential part of the body’s 24 hour biological cycle. An adult requires between 6 to 9 hours of sleep daily while children need at least 8 hours of sleep. While some adults may be able to function with 5 to 6 hours daily, it is not the norm. Inadequate sleep affects physical and mental functioning and well being in various ways. It may increase the risk of life threatening conditions like a stroke.
Feeling sleepy during waking hours is also known as excessive daytime sleepiness. It is a common symptom that occurs in many sleep-related disorders and various. This is where a person feels sleepy during the day and can occur despite sleeping at night. It is commonly seen with insomnia, sleep apnea, narcolepsy as well as conditions like diabetes, other endocrine disorders and heart disease.
Causes of Sleepy Feeling in the Morning
We all wake up in the morning feeling a bit sleepy or drowsy. This is the effects of the sleep hormones which wear off within a short period of time after waking. However, severe drowsiness, dizziness, fatigue or a persistent sleepy feeling may be the sign of some underlying disorder or disease. These sensations are symptoms that may occur with many different conditions. It is therefore important to seek medical attention to find the exact cause.
Too Little or Poor Quality Sleep
Both the quantity and quality of sleep on a daily basis are important to maintain well being and energy levels. Apart from an average of 8 hours of sleep around the same time everyday, sleep should not be continuous and undisturbed. A comfortable sleep environment, including the temperature of the room, bedding and even sleepwear can impact on the quality of sleep. Insufficient sleep for any reason is one of the main reasons for sleepiness during the day.
Narcolepsy is a chronic sleep-related disorder. A person with narcolepsy experiences severe sleepiness during waking hours (excessive daytime sleepiness) and may fall asleep suddenly. This can be dangerous if a person is driving a vehicle or operating heavy machinery. Despite sleeping for long hours, a person with narcolepsy still experiences excessive daytime sleepiness.
Sleep apnea is a common problem that can affect sleep quality. In sleep apnea, breathing stops momentarily while asleep which causes an interruption in the sleep cycle. Most people with sleep apnea do not realise that they have woken momentarily to restore breathing several times during the course of the night. Symptoms like unexplained morning fatigue and daytime sleepiness are the main symptoms.
Jet lag occurs when traveling long distances and across many time zones. It is more likely to occur with air travel. The extended travel disrupts the body’s circadian rhythm (biological clock) and this causes fatigue with daytime sleepiness. Gradually the sleep cycle restores within a few days once the body’s biological clock resets after traveling. If it persists then other causes need to be investigated.
Diabetes mellitus is an impairment in glucose control which leads to high blood glucose levels. Type 2 diabetes has become a common problem globally, and is associated with the rise in obesity across the world. The disturbance in blood glucose levels which occurs in diabetes causes several symptoms, including unexplained fatigue. This may be associated with constant sleepiness.
Hypothyroidism is lower than normal thyroid hormone levels which is usually due to an underactive thyroid gland. There are many reasons why thyroid gland activity may be depressed. Autoimmune disorders, genetic factors, pregnancy and infections are some of the possible causes of hypothyroidism. Since the thyroid hormones regulate the metabolism, lower levels will lead to unexplained tiredness and possibly sleepiness as well.
Several drugs can affect the sleep cycle and therefore cause a sleepy feeling after waking up. Some drugs like sedatives (sleeping pills) which are used to help to induce and maintain sleep can also cause daytime sleepiness if the drug has not worn out by the time a person awakes. Opioid analgesics (painkillers) may also have a similar effects. Conversely, the sleep cycle may be disrupted after stopping a certain drug.
Alcohol is a depressant and can cause sleepiness a short while after it is consumed. While it can help a person to fall asleep, alcohol does not give a good quality sleep. Therefore sleepiness may be persistent after waking. Illicit substances may also disrupt the quality of sleep despite inducing sleep. Various other substances should also be considered as a possible cause of unusual sleepiness if the symptom arises after using a specific substance.