Morning Headaches

Between 18% and 41% of patients with obstructive sleep apnea have experienced headaches upon awakening in the morning.

Two studies reported morning headaches associated with bruxism. A study that examined the sleep of women living with heavy snorers found that these women, in addition of suffering disturbed sleep and daytime sleepiness, also had morning headaches. Other studies also reported associations between morning headaches and periodic limb movement disorders. Morning headaches were also found in hypertension. Prior to our study, the prevalence of morning headaches in the general population was not known, although according to a Swedish study, 5% of the population awakened often or very often with headaches.

Surprisingly, although there is considerable literature about the association between the different subtypes of headaches (migraine, cluster headaches, tension headaches) and mental disorders, specially depressive disorders and anxiety disorders, to the best of our knowledge, no study has attempted to determine the status of mental disorders in the report of morning headaches.

METHODS

The studied countries were:

• the United Kingdom
• Germany
• Italy
• Portugal
• Spain

This represented about 206 million Europeans.

A two-stage design was used for all countries. The population of each country was:

• first divided according to its geographical distribution as per the official census data, then telephone numbers were randomly drawn in each geographical area.
• Second, within each household, a member was selected by age and gender using the Kish method (17) in order to maintain the representation of the sample and to avoid bias related to non-coverage error.

Participants had to first grant their verbal consent prior to proceeding with the interview. We excluded potential participants who had insufficient fluency in the national language, who had a hearing or speech impairment or with an illness that precluded the feasibility of an interview.

The participation rate was:

• 79.6% (4,972 of 6,249 eligible individuals) in the UK;
• 8.1% (4,115 of 6,047 eligible individuals) in Germany;
• 89.4% (3,970 of 4,442 eligible individuals) in Italy;
• 83% (1,858 of 2,234 eligible subjects) in Portugal;
• and 87.5% (4,065 of 4,648 eligible individuals) in Spain.

A total of 18,980 subjects participated in the study. The overall participation rate was 80.4%.

In relationship to morning headaches (i.e., present when the subject wakes up), this study uses using a sample of 18,980 subjects representative of the general population of five European countries to examine the importance of five categories of factors:

• socio-demographic determinants,
• use of psychoactive substances,
• organic diseases,
• sleep and mental disorders.

RESULTS

This study is the first to explore the associated factors of morning headaches in the general population using a large sample (N=18,980 subjects).

We found a prevalence of 7.6% of subjects who said they woke up at least sometimes with headaches, with a median duration in which they occurred of 42 months.

Our study is not without shortcomings. The primary purpose of these community-based surveys was to investigate sleep and mental disorders. Therefore, full description of the headaches, the localization and the intensity of the pain were not assessed. A study that attempted to classify morning headaches into the different categories of headaches (migraine, tension-type, cluster, cervicogenic headaches) was unable to fit nearly half of the patients with morning headaches into one of these categories (2).

Risk factors related to morning headaches were examined according to five main categories: sociodemographic determinants, use of psychoactive substances, organic diseases, sleep disorders and mental disorders.

SOCIO-DEMOGRAPHIC DETERMINANTS OF MORNING HEADACHES

Among sociodemographic determinants, we found that:

• being a woman,
• being middle-aged
• and being unemployed or a homemaker

were positively related to morning headaches.

A study that examined the frequency of morning headaches in a community-based sample did not find significant differences between men and women, but limited the analysis to subjects with heavy snoring and obstructive sleep apnea syndrome (1).

PSYCHOACTIVE SUBSTANCES AND MORNING HEADACHES

We also found a positive association:

• between heavy drinking (at least 6 alcoholic drinks per day) and morning headaches
• between the use of anxiolytic medication and morning headaches.

Subjects using these psychoactive substances were twice as likely to report morning headaches. In the studies that analyzed factors related to morning headaches, these two factors were rarely taken into account, although these two psychoactive substances have well-known depressive effects on the respiratory system. Lack of sufficient oxygenation during sleep may favor the occurrence of headaches upon awakening.

ORGANIC DISORDERS AND MORNING HEADACHES

Among organic disorders, we found that:

• subjects with hypertension or musculo-skeletal diseases had a higher risk of reporting morning headaches.
• Changes in blood pressure are likely to cause headaches.

Hypertensive headaches do not have specific diagnostic features, but are known to be most pronounced on awakening in the morning (26). However, as the results showed, the presence of hypertension alone is not sufficient to explain the presence of morning headaches: not all subjects with morning headaches have hypertension and conversely not all subjects with hypertension reported morning headaches.

HEAVY SNORING/OBSTRUCTIVE SLEEP APNEA SYNDROME AND MORNING HEADACHES

OSAS limits the airflow during sleep, causing repeated episodes of hypoxia. It also causes alterations in blood pressure control mechanisms. These two mechanisms can provoke headaches during sleep that may still be present upon awakening. Many believe that morning headaches are specific to sleep breathing disorders. This assertion is based on clinical trials that report reduction of the severity of morning headaches in OSAS patients treated with continuous positive airway pressure (2). However, most of these studies lack adequate control groups and/or assessment of possible confounders to provide strong support to whether morning headaches are specific to OSAS.

Our results do not support the uniqueness of this association. We did find that obstructive sleep apnea syndrome and heavy snoring made an independent contribution to morning headaches, but they were neither the only nor the strongest predictors of morning headaches. Other studies also reported the non-specificity of morning headaches to sleep breathing disorders (27,28).

OTHER SLEEP DISORDERS AND MORNING HEADACHES

In our study, we extended the associations to other diseases and disorders that may influence the occurrence of morning headaches.
Among sleep disorders, we found that:

• dyssomnia not otherwise specified, which included restless legs syndrome, periodic limb movement disorder and sleep disorders with multiple possible causes, had the highest association with morning headaches.
• The association between morning headaches and insomnia disorders or other sleep disorders involving a lack of sleep is not so surprising because sleep deprivation is a well-known cause of headaches (29).

MAJOR DEPRESSIVE DISORDER AND MORNING HEADACHES

We also found that subjects with a major depressive disorder were at high risk of waking up with headaches. This disorder had one of the highest odds ratios in the multivariate model. Our data are cross-sectional, therefore, we cannot make causal reference between the morning headaches and depression.

Some longitudinal studies also had explored the association between depression and migraine or chronic headaches.

For example, Breslau et al. (14) found that subjects with migraine and those with severe headaches were three times more likely to have a major depression in their lifetime and conversely, subjects with migraine or severe headache were two to three times more likely to later develop a major depression.

Similarly, in a longitudinal study, Pine et al. (15) reported that adolescents with major depression at the first evaluation had nearly a tenfold increased risk of developing headaches during the next seven years. It appears the associated migraine-depression is a bi-directional relationship; the presence of one increasing the risk of appearance of the other.

However, to what extent waking up with headaches is related to depressive disorders is little documented. It is likely that the relationship is similar to that reported for migraine or severe headache and depression: morning headaches can be a somatic manifestation of depression or morning headaches can be a cause of depression.

CONCLUSIONS

Subjects with headaches almost all have either an organic disease or a sleep or a mental disorder, but most often several factors are involved.

Our results clearly show that it is misleading to relate morning headaches only to sleep-related breathing disorder. An effort should be made to better describe morning headaches in subjects with obstructive sleep apnea before concluding to the specificity of this association.

Recurrent morning headaches in about 80% of cases are related to an identifiable organic, mental or sleep disorder. Therefore, physicians should be aware of the multiplicity of factors involved in the complaint of morning headaches and the necessity of conducting a thorough interview with the patient to identify all possible factors, because it is most likely that many factors are involved.