Why do I wake up tired after a full night's sleep?

Waking up tired after what should have been enough sleep usually means the sleep itself wasn't as good as the hours suggest. Normal morning grogginess, sleep broken up by alcohol, stress or noise, and sleep disorders such as sleep apnea are the common reasons. If it keeps happening, the NHLBI says it's worth talking to your doctor.

Is some morning grogginess normal?

Yes, some morning grogginess is normal. The Sleep Foundation describes sleep inertia as the grogginess, disorientation and drowsiness that follows waking. It says the feeling generally lasts 15 to 60 minutes, but may last up to a few hours.

So if you feel slow for the first half hour and then come right, that's ordinary. The Sleep Foundation suggests consistent wake-up times and natural light in the morning to help. It also says that people with certain sleep disorders are more likely to have stronger or longer sleep inertia, which is one reason not to brush off grogginess that lasts all day.

Why can a full night still leave you tired?

A full night can still leave you tired because hours in bed and good sleep aren't the same thing. The NHS lists not getting enough sleep or finding it hard to sleep, an unhealthy lifestyle, stress, depression, hormonal changes, illness and some medicines among the common causes of tiredness.

Start with the number. The NHLBI lists 7 to 8 hours a day for adults, based on recommendations from the American Academy of Sleep Medicine, and the NHS gives a range of 7 to 9 hours. If you've been running short through the week, the NHLBI explains that sleep loss adds up into a sleep debt. Sleeping in on days off can help you feel better, but it can also upset your body's sleep and wake rhythm. Our guide to how much sleep adults need goes into the numbers.

If you are getting your hours, the quality of the night is the next thing to look at. Sleep that's broken up by waking, even briefly, can leave you feeling as though you barely slept. If you wake in the small hours, why you wake up at 3am covers the usual reasons.

Does alcohol make you wake up tired?

Yes, alcohol can make you wake up tired. A 2013 review of studies on alcohol and sleep in healthy volunteers found that at all doses, alcohol helped people fall asleep faster and made the first half of the night more consolidated, but increased sleep disruption in the second half. The same review found that the first period of REM sleep was delayed at all doses.

So a drink can make you feel as though you dropped off easily, while the back half of the night is more broken. The NHS includes not drinking too much alcohol in its advice for tiredness.

Could it be sleep apnea?

Sleep apnea could be why you wake up tired, and it's the cause not to miss. With obstructive sleep apnea, the airway repeatedly narrows or closes during sleep. The American Academy of Sleep Medicine explains that this causes many arousals through the night, sometimes several hundred in severe cases, and that people may be completely unaware of them. The result is sleep that doesn't refresh you, however long you spend in bed.

The AASM lists five warning signs:

• Snoring, often noticed by a bed partner.
• Choking or gasping during sleep, or silent pauses in breathing.
• Fatigue or daytime sleepiness.
• Obesity.
• High blood pressure.

It also lists unrefreshing sleep, insomnia, morning headaches, waking at night to urinate, difficulty concentrating and irritability among other common symptoms. The NHLBI adds dry mouth to its list of things you may notice yourself, and points out that you may not know about the nighttime symptoms until someone tells you.

The NHS suggests asking someone to stay with you while you sleep so they can check for symptoms. It says to see a GP if your breathing stops and starts, you make gasping, snorting or choking noises, or you always feel very tired during the day, and it warns that sleep apnea can be serious if it isn't diagnosed and treated. For help telling the two apart, see snoring vs. sleep apnea, and sleep apnea treatment options covers what doctors offer.

Could another health problem be the cause?

Sometimes another health problem is the cause of waking up tired. The NHS lists several conditions that can cause ongoing tiredness, including iron deficiency anaemia, diabetes, an overactive thyroid and ME/CFS. Each tends to come with other symptoms, such as feeling very thirsty and peeing more often with diabetes, or shortness of breath and pale skin with anaemia. The NHS is clear that you shouldn't self-diagnose, and that a GP may arrange blood tests to check.

The NHLBI also notes that stress, anxiety, medical conditions and some medicines can interfere with sleep.

What about waking up with a dry mouth?

If you wake up tired and parched, mouth breathing may be part of the picture, and our guide to why you wake up with a dry mouth explains the link. Dry mouth is also on the NHLBI's list of sleep apnea symptoms, so check the warning signs above first.

If those don't apply, helping your nose do the work is worth a try. Start with a clear nose. A nasal strip can help if it feels stuffy at night, and how to unblock your nose before bed has other ideas. For adults who breathe easily through the nose but find their mouth falls open, mouth tape is another option. The Sleep Foundation explains that a strip of porous tape over the lips gently encourages nasal breathing during sleep. It's clear that the research is still limited and that tape isn't a treatment for sleep apnea, so think of it as an experiment for comfort rather than a fix for tiredness. Try the nose test before you start.

If you want to try mouth tape and nasal strips together, our pick is the Titan Sleep System, which pairs TitanAir Nasal Strips with Titan Mouth Tape.

What can help you wake up more refreshed?

To wake up more refreshed, the NHS suggests a few habits for tiredness:

• Stick to the same sleep times.
• Relax for a couple of hours before bed, for example by reading or listening to music.
• Keep your sleeping area not too bright, noisy or warm.
• Avoid eating, caffeine and exercise in the couple of hours before sleep.
• Avoid screens in the hour before sleep.

A regular wake-up time does double duty, since the Sleep Foundation also suggests it for reducing morning grogginess. Sleep hygiene tips that are worth trying has more.

When should you see a doctor?

The NHLBI says you should talk with your doctor if you sleep more than 8 hours a night but don't feel well rested, since you may have a sleep disorder or other health problem.

The NHS says to see a GP if you've been feeling tired for a few weeks and you're not sure why, if tiredness affects your daily life, or if you've been told you make gasping, snorting or choking noises while you sleep. Bringing someone who has watched you sleep can help, and the NHS notes that if sleep apnea is suspected you may be referred for a sleep test, which can often be done at home.

Read next

• Snoring vs. sleep apnea: how to tell the difference
• Why do I wake up with a dry mouth?
• CBT-I: the insomnia treatment sleep doctors recommend first

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.