Drowsiness: Causes, Treatments, and Prevention

  • Drowsiness during the day is an important problem which can decrease the quality of life.
  • The severity can range from mild daytime sleepiness to irresistible episodes of falling asleep in dangerous situations.
  • There are many causes for drowsiness including shortened or irregular nighttime sleep, disturbances in the sleeping environment, poor sleep habits, sleep disorders, and medical conditions.
  • If daytime drowsiness is persistent, consultation with a physician is indicated to determine the cause

What is Drowsiness

Feeling drowsy during the day is a sensation which we have all experienced after a night of poor sleep.  It is a sensation of sleepiness, normally occurring at night as we falling asleep, weaving its way into our waking consciousness in varying degrees.  This feeling can range from a vague drowsiness which is merely annoying to an overwhelming, irresistible sensation of fighting to remain awake.  The terms excessive daytime sleepiness or hypersomnia (from the Greek meaning in excess and Latin meaning sleep) are also often used to refer to daytime drowsiness.  If the sensation of drowsiness becomes overwhelming, we might actually fall asleep during the day at times when it is crucial to remain awake and alert.  Learn how to fall asleep. We may even “wake up” during the day without realizing we have fallen asleep.  Drowsiness which invades our waking life at the wrong times can create a multitude of undesirable and possibly dangerous consequences.

For most of us, feeling a little drowsy at times is not of great concern.  However, when drowsiness begins to interfere with our ability to remain awake at work or school, driving a car, reading, attending church, watching television, or in other quiet circumstances, fighting drowsiness can begin to control our life.  When drowsiness intrudes into life to this extent, we should consider the reasons for this drowsiness.

The most basic purpose of sleeping well at night is to keep us alert and functioning at our best during the day.  Good quality sleep and adequate amounts of sleep are essential for good daytime functioning.  When drowsiness begins to interfere with waking, it is possible that some aspect of our nighttime sleep is disturbed or that there is another problem.  Drowsiness may be caused by a straightforward, simple issue such as having a busy schedule and not getting enough sleep at night.  However, there may also be medical problems or serious sleep disorders such as sleep apnea present.  In this article we will discuss the causes for drowsiness as well as how to minimize drowsiness during our waking life.

Before we discuss possible causes for drowsiness, let’s review some common questions.  Remember that whatever interrupts sleep at night or which causes us to lose time asleep during the night potentially contributes to the development of daytime drowsiness.

“What is so important about feeling a little drowsy?  If I move around and drink coffee during the day, I can stay awake just fine.”

After a night of sleep you should feel refreshed when you wake up.  If you require a stimulant like caffeine which is present in coffee, tea, soft drinks, energy drinks, and chocolate to stay awake, it is likely that you are not getting enough sleep or that your nighttime sleep is not of good quality.  Furthermore, if you drink caffeine in the evening, this may cause your sleep that night to be even more disturbed.  It is true that physical movement may also allow you to feel more alert, but continuous movement is not a realistic means of keeping awake.

“Sometimes when I am at school or in a meeting at work, I seem to “zone out”.  Does this mean that I am drowsy during the day?”

 Although losing focus in these situations is not necessarily a sign of sleepiness, it could mean that you are momentarily drifting into sleep, sometimes for fractions of a second, without even being aware of doing so.  The term microsleeps is one which is often applied to these very brief sleep periods.  If you find that you repeatedly have a problem with concentration or fogginess in your thinking, microsleeps may be affecting you.

“Aren’t some people just naturally sleepy?  My dad is sleepy, I’m sleepy, and my grandfather is always falling asleep during the day.”

 There are some sleep disorders for example, narcolepsy, periodic limb movements, sleep walking, and sleep apnea, which are known to have either a genetic basis or to run in families.  Of particular note is that older persons often seem to be “naturally” sleepy during the day.  However, older people are more vulnerable to irregular sleep schedules and may not obtain enough sleep at night.  In addition, the incidence of sleep disorders increases with advancing age.

“My spouse tells me that I am always asleep when I sit down to watch television.  I have even been told that look like I am asleep when I am driving and I have been told that I start to drift between lanes of traffic.  I don’t believe that it is possible to be asleep in these circumstances, and not even know it.   I am positive that I am not asleep.” 

 No one chooses to sleep when they are driving a car.  Drowsy driving is clearly very dangerous to the driver as well as to others.  However, sleepiness can become so extreme and overpowering that you no longer have the voluntary choice to remain awake.

There is a stigma attached to falling asleep during the day in situations where you are supposed to be awake.  Drowsy people may be labeled as being lazy or unmotivated, and they may be accused of not “trying” to stay awake.  So, it is natural to deny being asleep in these situations.  However, the physiology of your body, rather than your conscious mind, begins making the decisions for you in conditions of extreme drowsiness.  As we discussed earlier, it is possible to momentarily fall asleep without being aware of doing so.  Furthermore it is possible to be in the lightest stage of sleep which is Stage 1 sleep and feel as though you are still awake. It is crucial to recognize though that severe drowsiness leading to actually falling asleep is not under your voluntary control.  This problem requires medical evaluation and treatment.  If you are told repeatedly that you appear to be asleep in circumstances such driving a car, even though you do not feel as though you are asleep, you should not dismiss these observations.

Causes for Drowsiness

There are many different causes for daytime drowsiness.  In general, anything which delays, interrupts, or shortens your sleep has the potential to cause drowsiness during the day.  These same factors also apply to shift workers who work at night and sleep during the day.  Here are some of the most common causes associated with daytime drowsiness.

Your sleeping environment may be disturbing you

If you are drowsy during the day, your bedroom environment may be contributing to poor quality nighttime sleep.  Some of these factors may seem relatively unimportant or trivial.  However, nothing is unimportant if it bothers you when you are trying to sleep.  Consider whether the following aspects of your sleeping environment may be bothering you.

  • My bed is not comfortable
  • My pillows are too lumpy or too flat
  • My bedcovers feel too heavy
  • My pajamas or bed clothes are not comfortable
  • The curtains let in light from the outside
  • The temperature in the room frequently seems too hot or too cold
  • There are noises in the house, such as appliances or heating and air conditioning units going on and off, which wake me
  • My cat or dog comes in and out of my room at night or my pet sleeps in my bed
  • Sometimes I don’t feel secure or safe in my bedroom
  • The LED displays on my alarm clock and other electronics in the room are bright
  • My bed partner snores loudly
  • My bed partner thrashes and moves during sleep
  • My bed partner has a different time of going to bed from me
  • Other people, including babies and children, in my house wake me up during the night
  • I leave the television on when I am in bed trying to sleep
  • I leave my cell phone on when I sleep or I sleep with my cell phone in bed with me so that I can answer calls and reply to texts during the night
  • Outside noises such as garbage trucks or traffic wake me up
  • There are other noises or disruptions unique to my sleeping environment

Shift workers who work at night and sleep during the day may face even more challenges in eliminating these disturbing elements from their sleeping environment…

 You may not be getting enough sleep at night

It may seem obvious, but if you do not get enough sleep at night, you will invariably feel drowsy during the day.  We are a very sleep deprived society, and most adults do not regularly obtain sufficient sleep.  There is a myth that sleep is a waste of time, and we often hear reports that public and business figures can function effectively on three or four hours of sleep per night.  However, there is a great deal of research which suggests that not enough sleep can be associated with serious medical conditions such as high blood pressure or diabetes.  There is also evidence to suggest that insufficient amounts of sleep may even affect how long we live.

So what is the ideal amount of sleep that we should obtain at night?  It is recommended that at least seven hours of sleep per night for adults is optimal.  Even children and teenagers may not obtain an ideal amount of sleep.  Guidelines from the AASM published last year suggest the following sleep amounts per 24 hours (including daytime naps) to promote good health for the following age groups.

  • Infants (4-12 months) 12 – 16 hours
  • Children (1-2 years) 11 – 14 hours
  • Children (3-5 years) 10 – 13 hours
  • Children (6-12 years)   9 – 12 hours
  • Teenagers (13-18 years)   8 – 10 hours

Your schedule of sleep and waking times may not be regular

We have emphasized how important it is to have an adequate number of sleeping hours each night to keep ourselves from becoming drowsy during the day.  Besides the amount of sleep we should obtain, there is a second important factor in determining how refreshed we feel during the day.  This second factor is the regular timing of sleep during each 24 hour period.  This is referred to as the circadian (a term from the Latin meaning about a day) timing of sleep during each 24 period of day and night.

Besides a normal amount of sleep each night, we must also maintain a regular schedule of going to bed each night and getting up each morning during each 24 hour period.  There are significant changes in body temperature and hormone secretions that vary according to circadian cycles of sleep and waking.  For example, it is well known that there is a decline in body temperature in the evening hours anticipating the time of sleep onset and a rise in body temperature which occurs in anticipation of waking.

Keeping a regular sleep-wake schedule is crucial for good sleep.  Most of us usually keep a fairly regular schedule of sleeping and waking times during the work week.  But then the weekend comes.  We often feel on weekends as though we are finally free to go to bed and get up whenever we want, without paying much attention to our schedule.  Nothing could be further from our biology in keeping our sleep on track.

Since we often do not have a pressing need to wake up early on a Saturday morning for work, we may stay up much later than usual on a Friday night.  As a result we may stay asleep longer and wake up later on a Saturday morning…  This pattern is often repeated again from Saturday night to Sunday morning.  By altering our time of going to bed later and then getting up several hours later, even for just a weekend, we send our sleep-wake cycle confusing messages about when we should sleep and wake.  Then, on Sunday night, it may be very difficult to fall asleep at our normal work week time and very difficult, if not impossible, to wake up on time for work on Monday morning.  We should also be aware that taking prolonged daytime naps lasting more than 30 minutes or so can result in producing irregularity in our sleep schedule.

You do not have a regular bedtime routine

 Everyone has had the experience of a stressful day and then having trouble falling asleep.  To help yourself fall asleep when you finally do get into bed, plan on mentally and physically relaxing to prepare yourself for sleep.  Taking a few minutes to sort out problems from the day, eating a small snack, or reading before you turn out the lights can help you fall asleep.  Besides mental relaxation, mild stretching exercises or deep breathing exercises can help you physically relax.  A relaxed mind and a relaxed body will help ease your transition to sleep so that you to obtain your usual amount of sleep and do not feel drowsy the next day.

You drink caffeine or eat heavy meals too close to bedtime

 Caffeine is a stimulant, and it is contained in beverages such as coffee, tea, soda, and energy drinks.  Chocolate also contains caffeine.  Caffeine can result in nighttime sleep disruption and then drowsiness may be increased the next day.

Your favorite heavy or spicy meal may cause an upset stomach and prevent you from falling asleep.  A light snack before bed, however, may be of help in falling asleep.  .

You exercise too close to bedtime

 In addition to good quality sleep and a balanced diet, regular exercise is one of the foundations for good health.  Studies have shown that exercise can improve sleep quality.  However, the timing of exercise is important so that it does not interfere with our sleep.  Often in our busy lives it is difficult to schedule exercise during the day.  If you cannot fit exercise in during the day, then exercise in the evening hours may be your only option.  However, following exercise, you may feel more awake immediately afterwards due to elevations in heart rate or blood pressure.  If you then try to sleep immediately after exercise, you may have trouble falling asleep.  You should allow a cool down period lasting a couple of hours before trying to sleep.

 You use alcohol to fall asleep

 Alcohol can result in falling asleep more quickly at the beginning of the night, and there is a myth that alcohol is beneficial for sleep.  Many people do use alcohol as a temporary “sleeping pill”.  However, studies have shown that even though alcohol can speed up the process of falling asleep, alcohol invariably causes frequent brief awakenings and restless sleep, resulting in daytime drowsiness.

Alcohol consumption alters the normal sequence of sleep stages during the night and most notably suppresses rapid eye movement sleep (REM) sleep or dreaming sleep.  Additionally, alcohol can suppress breathing during sleep.  The volume and frequency of snoring can increase, indicating a partial blockage of the airway.  The airway can also become completely obstructed resulting in the appearance of actual episodes of stopping breathing during sleep.  The duration of these episodes ranges from 10 seconds or so to over a minute.  Only a few of these nonbreathing episodes may appear, but it is not uncommon for several hundred episodes to occur during sleep  Significant changes in heart rate, blood pressure, and oxygen levels typically occur.  Each time that breathing stops and then begins again, there is a brief arousal from sleep.

You can see that using alcohol for sleep is not only decreases sleep quality, but also that there are potentially dangerous effects on the functioning of your body.

You take medications or have a chronic illness

Many prescription medications and over the counter sleep aids like melatonin can disturb nighttime sleep resulting in sleepiness during the day.  Prescription medications can also cause drowsiness the day.  Some long acting sleeping pills which may improve your ability to fall asleep at night can also “hang over” effects the next day, causing you to feel drowsy.  Most of the newer sleeping pills do not have these kinds of daytime effects due to their shorter action.  However, do not take a sleeping pill of any kind during the middle of the night in order to fall back asleep since the effects of the sleeping pill may extend to your daytime hours.

If you notice that you seem to feel drowsier than usual during the day after taking a medication, talk to your sleep doctor about the possible contribution of these medications in disturbing sleep at night or in causing you to feel sleepy during the day.

Medical illnesses, hospitalizations, and chronic pain are frequently associated with disruption of nighttime sleep and subsequent sleepiness during the day.  Once again it is important to talk to your physician about your symptoms.

You may have a sleep disorder

If your daytime drowsiness is persistent despite your best efforts to follow these suggestions, it is important to discuss this issue with your physician about your problem.  He or she may perform various tests to determine if another medical problem is causing your drowsiness.  You may also be referred to a Sleep Center for an overnight sleep test.  During this test, your brain and muscle activity along with your breathing, heart rate, and oxygen levels are continuously recorded and then analyzed.  Sometimes a daytime nap test, the Multiple Sleep Latency Test (MSLT), is also performed to evaluate the degree of daytime sleepiness.  Both of these tests can determine if you have a disorder which is specific to your sleep that cannot be detected during the day.

Some sleep disorders which are associated with the symptom of daytime drowsiness include the following:

Sleep apnea is a disorder in which loud snoring, breath holding episodes accompanied by oxygen decreases, and restlessness occurs during sleep.  A brief arousal from sleep occurs following breath holding episodes when breathing begins again, resulting in a very brief arousal.  Hundreds of these episodes are often present, severely disturbing sleep. During the day, drowsiness related to sleep apnea can be extreme with patients often actually falling asleep driving a car or in other dangerous situations.  Middle-aged males who are overweight and who have with a large neck, a crowded throat often with tonsils present, and high blood pressure appear to be most likely to have sleep apnea.  However, sleep apnea can affect both males and females of all ages from babies to the elderly

Restless legs are a creeping, crawling, uncomfortable, unpleasant sensations in the legs which occurs sitting quietly during the day, but which becomes most disruptive as someone is trying to fall asleep.  The only relief of these sensations is to walk or move the legs, but then the sensation returns requiring further movement.  It is not hard to imagine how this disorder could prevent you from falling asleep or waking up during the night.

Periodic limb movements frequently accompany restless legs.  These leg movements are repetitive, rhythmic jerking movements most often of the legs, but which can also occur in the arms, during sleep.  Periodic limb movements are often completely unknown to the sleeper, but a bed partner is able to observe these rhythmic movements.  Hundreds of these jerking movements during sleep result in brief arousals and awakenings and then sleepiness during the day.  If a person with restless legs is finally able to fall asleep at night, they often have periodic limb movements during sleep.

Narcolepsy is associated with extreme sleepiness during the day, and it is thought to be a less common sleep disorder than sleep apnea or restless legs/periodic limb movements.  Narcolepsy is associated with an abnormality in the timing of REM sleep (rapid eye movement) or dreaming sleep.  Symptoms of narcolepsy can include cataplexy (loss of muscle tone during the day with strong emotions), sleep paralysis (an inability to move upon falling asleep or waking up), and hypnagogic hallucinations (vivid, dreamlike experiences which occur during waking before sleep onset).

Circadian rhythm disturbances are a misalignment between a desired schedule of sleeping and waking times and the times that you actually feel like sleeping and waking.  In advanced sleep phase syndrome if your desired sleep times are between 10 pm and 6 am, you may feel, for example, ready to sleep at 7 pm and then wake up early at 3 am.  In delayed sleep phase syndrome, you may not feel sleepy, for example, until 1 am and then wake up late at 9 am.  In both of these situations you can feel drowsy during the day at times when you want to remain alert.

Sleep walking, sleep talking, night terrors, nightmares, enuresis (bed wetting), bruxism (tooth grinding), and REM behavior disorder (RBD) are all disorders which can disturb sleep and cause sleepiness during the day.  Some of these disorders such as sleep walking, enuresis, and night terrors (awakenings during the night with screaming or crying but the sleeper has no memory of the event) are most common in children.  In adults, RBD is associated with vigorous and sometime injurious behavior to themselves and their bed partner.  This disorder occurs during REM sleep, a sleep stage in which there is normally muscle paralysis and an inability to move.

These are some of the most common sleep disorders which can disturb sleep and which can result in drowsiness during the day.  There are also other sleep disorders which are associated with daytime sleepiness that can be diagnosed with overnight sleep studies.  If you are aware of unusual behavior during sleep or others sleeping around you report that you have these symptoms, talk to your physician.  A comprehensive evaluation of these sleep problems can be obtained in Sleep Clinics.

Prevention of Drowsiness

 How can daytime drowsiness be improved or prevented?  Here are some suggestions to improve your nighttime sleep and decrease daytime drowsiness.

Take an inventory of your bedroom and sleeping environment to identify potential problems

 Examine your bedroom and sleeping environment carefully to identify what might be bothering your sleep at night and causing you to feel drowsy during the day.  Some possible remedies for issues which you might discover include the following.

  • If your mattress feels uncomfortable and there are obvious lumps or bumps in the mattress, you might consider replacing it. However, there is not a “magic” mattress which will assure that you have a perfect night of sleep.  You should pick a mattress that feels comfortable to you.  Changing your pillows, bedcovers, and bedclothes may increase your comfort.  Examine and if necessary replace your curtains or blinds so that your bedroom is dark and light from street lights or early morning light does not shine in your room.  Black out curtains may also be helpful.
  • Most people sleep more comfortably in a room which is cool rather than warm. Lowering your thermostat to decrease the temperature during your time in bed may improve your sleep…
  • Try to identify sources of noise in your room and house which wake you during the night and eliminate them.  A room fan or a “white noise” machine may help mask sounds.  You might also consider soft earplugs to muffle noises.
  • Pets can be surprisingly disruptive to sleep by jumping off and on the bed or coming in and out of the room at night. Consider training your pet to stay off your bed and to sleep in his/her own dedicated sleeping area away from your bed.
  • Feeling secure in your house and bedroom is important for relaxation and sleep. If you have security concerns about your locks or access to your home, address these issues.
  • That tiny little light on your alarm clock can be a surprising source of sleep disruption. Turn your clock around so that you cannot see its light or check the time when you should be trying to sleep.  Turn off or cover the lights on other electronic equipment in your bedroom.
  • The sleep problems of other persons in your household also become your sleep problems if your sleep is disturbed by them. A snoring, thrashing bed partner can be a source of sleep disruption, often forcing one or the other person to sleep in a separate room.  If your partner’s sleep has become your sleep problem, observe your partner closely for an interrupted pattern of snoring and if there are breath holding episodes during sleep.  Also observe any patterns of jerking or twitching movements during sleep.  Consultation with a physician may result in a referral to a Sleep Center for evaluation, diagnosis and treatment of your partner’s sleep problem.

If your child is having difficulty with sleep or he/she is drowsy during the day, follow these same suggestions for making sure that your child’s sleeping environment and sleep habits encourage good sleep.  Also be aware that children of all ages, like adults, can have sleep disorders which are diagnosed and treated in a Sleep Center.

  • Do not sleep with your television on, even though you may believe that you need the television to sleep. The light and the sound from the television will invariably disturb your sleep.  If you feel as though your bedroom is “too quiet” when you get into bed to sleep, a white noise machine when you sleep or relaxing music at a low volume may help.
  • Do not take your cell phone to bed with you. Unless you are expecting emergency calls do not plan on answering your cell phone during the night.  Do not text on your cell phone when you are trying to sleep.  Ideally, your cell phone will be off during the night, but this, of course, is not always possible.

Be sure you are spending enough time in bed each night.

As we previously discussed, recent guidelines from the American Academy of Sleep Medicine recommend at least seven hours of sleep per night for adults with more sleep required for children and adolescents.  Plan your schedule so that you obtain at least this amount of sleep each night.  You may find that you require more than seven hours of sleep to feel fully alert during the day, and you should increase your sleep amounts, if necessary, to feel at your most alert.  Remember that at least seven hours of sleep, not the total amount of sleep averaged across several days, is your goal.  You cannot “make up” lost sleep, so plan on this amount during both the work week and on weekends.

Keep a regular schedule of going to bed at night and getting up in the morning.

Besides getting enough sleep at night, it is of importance to follow a regular schedule both during the work week and on weekends.  This allows your body to establish a regular 24 hour cycle of sleeping and waking times.

It is very helpful to keep a daily diary to track both the amounts and timing of sleep.    By recording the time you go to bed and get up in the morning over a period of two to four weeks, you will be able to determine if you are keeping a regular schedule with enough time in bed at night.

Limit your consumption of caffeine and meals near bedtime

 Do not drink caffeine containing beverages including coffee, tea, or energy drinks in the evening.  Chocolate contains caffeine and may also bother your sleep.  Do not eat spicy or heavy meals in the evening.

Do not drink alcohol to “improve” your sleep

The myth of alcohol being “good” for sleep is only a myth.  However, many people believe that alcohol is beneficial for sleep.  In fact alcohol causes fragmented sleep as well as alterations in normal sleep patterns as well as suppression of the respiratory system.  Do not drink alcohol before bed.

Put the brakes on your racing mind when you are trying to sleep

 You have had a busy day at work or at home with problems, both big and small, popping up like uninvited weeds in a well manicured lawn.  At last you are in bed, it is quiet and you have finally have uninterrupted time to think about these problems and try to find solutions.  This is probably the worst time to think about your problems since your mind will start to fight sleepiness when you should be sleeping.  However, it is easier said than done to make yourself to stop thinking so that you can sleep, and much of the time we are unsuccessful in controlling our thoughts so easily.

If you know that this often happens as you are falling asleep, a relaxing bedtime routine will help.  Plan to allot time for thinking about these issues before you get in bed.  You can schedule time before getting into bed to think about, devise solutions for, and even write down your thoughts before trying to sleep.  Once this scheduled “thinking time” is over, you can devote yourself to falling asleep

Talk to your physician

You may be reluctant to discuss daytime drowsiness with your physician because it may seem to you that sleepiness is a trivial problem in comparison to other serious diseases.  Nothing could be further from the truth.  There is recognition in the medical community of the serious consequences of sleep disorders.  Not only can daytime drowsiness can have significant impact upon our quality of life, but it may be a sign of a serious medical conditions such as sleep apnea.  Drowsiness may also be the result of medications or a symptom of some other medical condition not specifically related to sleep.  There have been remarkable advances in our understanding and treatment of sleep and sleep disorders in the last decade, and your physician will be able to assist you in finding an answer.  In addition to talking to your physician, you may also want contact an AASM accredited Sleep Center in your area.  These facilities are staffed by physicians board certified in sleep medicine that can answer your questions or direct you to literature on sleep and sleep disorders.

As we have seen, drowsiness during the day can have many different causes, but there are solutions.  Try to assess your own sleep habits with a critical eye and then discuss the problem with your physician.  We typically feel at our best and most productive after a night of good sleep so make the goal of quality sleep a part of your overall good health.


Kristyna M. Hartse, Ph.D.

Diplomate, American Board of Sleep Medicine (ABSM)

Fellow, American Academy of Sleep Medicine (AASM)

Registered Polysomnographic Sleep Technologist (RPSGT)

Registered Sleep Technologist (RST)

Certification in Clinical Sleep Health (CCSH)

Suggested reading

Recommended amount of sleep for a healthy adult:  A joint consensus statement of the American Academy of Sleep Medicine and the Sleep Research Society.  Journal of Clinical Sleep Medicine, Vol 11, 2016.

Recommended amount of sleep for pediatric populations:  A consensus statement of the American Academy of Sleep Medicine.  Journal of Clinical Sleep Medicine, Vol 12, 2016, 785-786.

Kryger, Meir  The mystery of sleep.  Yale University Press, 2017.  This book covers many different aspects of sleep and sleep disorders written for the general public.  It is available


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