Morning Headaches May Be a Sign of Obstructive Sleep Apnea

Higher Carbon Dioxide Levels May Increase Pressure in the Brain

A woman wakes with a headaches. Getty Images

If you wake up with a morning headache, you may seek the cause to identify the most appropriate treatment. It is somewhat surprising to realize that difficulty breathing during sleep may actually cause these headaches. How does obstructive sleep apnea contribute to morning headaches? When should another cause be considered?

There are a handful of headache types, and most people who experience them know the cause of their pain.

Tension headaches are the most common. These may be prompted by muscle tension, especially tight muscles in the neck that cause pain at the back of the head. Sinus headaches may occur in association with nasal congestion or allergies. Migraines are associated with vision changes, nausea and vomiting, and incapacitating pain. Cluster headaches are brutally painful and occur with eye redness and other findings. Rebound headaches can even occur if pain medications are overused. Many headaches are relieved by sleep, but why might headaches be noted first thing upon awakening?

Obstructive sleep apnea is a condition that disturbs breathing during sleep.  It is characterized by pauses in breathing that last at least 10 seconds and are associated with fragmented sleep, awakenings, or drops in the oxygen levels of the blood. Other symptoms of sleep apnea include:

  • Excessive daytime sleepiness
  • Snoring
  • Gasping or choking in sleep
  • Witnessed pauses in breathing
  • Urinating at night (nocturia)
  • Insomnia (frequent nighttime awakenings)
  • Dry mouth at night
  • Teeth grinding (bruxism)
  • Nocturnal heartburn
  • Palpitations
  • Night sweats
  • Concentration and memory problems
  • Mood problems

Obstructive sleep apnea occurs when the upper airway collapses, most typically due to shifts in the tongue and the soft palate, blocking airflow from the nose and mouth to the lungs.

As a result, oxygen cannot be brought in and carbon dioxide cannot be expelled. The carbon dioxide levels of the blood increase, most prominently in the case of obesity hypoventilation syndrome.

Carbon dioxide affects the size of blood vessels within the brain. The brain has a priority on resources. If inadequate breathing is occurring, the brain wants to preserve its access to oxygen and function. As a result, increased carbon dioxide levels dilate the brain’s arteries. This increases blood flow. In turn, this increases pressure within the skull, which is a confined space. Therefore, the gradual accumulation of carbon dioxide due to inadequate breathing in sleep can contribute to headaches that are noted upon awakening.

Frequently, morning headaches due to sleep apnea will fade in the first hours of the day as normal breathing resumes. Once awake, the airway is restored and the extra carbon dioxide is gradually blown off. Blood vessels in the brain decrease in size and the pressure eases.

These headaches will resolve without the use of pain medications.

Morning headaches due to sleep apnea may be described as an ache, rather than a sharp pain. They are not usually extremely painful and may vaguely affect the forehead or temples and are bilateral. The headaches do not occur at other times in the day. They are not associated with vision changes, nausea and vomiting, weakness, numbness, or dizziness. Positional headaches may also be associated with other conditions and assessment by a neurologist may be indicated if they persist or if other findings are present.

If you have morning headaches due to sleep apnea, treatment with continuous positive airway pressure (CPAP) can be highly effective. This will often decrease the frequency, intensity, and occurrence of these headaches. If the headaches do not resolve, consider further assessment to ensure another cause is not present.


Kryger, MH et al. "Principles and Practice of Sleep Medicine." Elsevier, 5th edition, 2011.

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