The aim of the study was to evaluate the association between sleep disturbance and headache type and frequency, in a random sample of participants in the third Nord-Trøndelag Health Survey. The headache diagnoses were set by neurologists using the ICHD-2 criteria performing a semi structured face-to-face interview. Sleep problems were measured by the two validated instruments Karolinska Sleep Questionnaire (KSQ) and Epworth Sleepiness Scale (ESS). Among 297 participants, 77 subjects were headache-free, whereas 135 were diagnosed with tension-type headache (TTH), 51 with migraine, and 34 with other headache diagnoses. In the multivariate analyses, using logistic regression, excessive daytime sleepiness, defined as ESS ≥ 10, was three times more likely among migraineurs compared with headache-free individuals (OR = 3.3, 95% CI 1.0–10.2). Severe sleep disturbances, defined as KSQ score in the upper quartile, was five times more likely among migraineurs (OR = 5.4, 95% CI 2.0–15.5), and three times more likely for subjects with TTH (OR = 3.3, 1.4–7.3) compared with headache-free individuals. Subjects with chronic headache were 17 times more likely to have severe sleep disturbances (OR = 17.4, 95% CI 5.1–59.8), and the association was somewhat stronger for chronic migraine (OR = 38.9, 95% CI 3.1–485.3) than for chronic TTH (OR = 18.3, 95% CI 3.6–93.0). In conclusion, there was a significant association between severe sleep disturbances and primary headache disorders, most pronounced for those with chronic headache. Even though one cannot address causality in the present study design, the results indicate an increased awareness of sleep problems among patients with headache.

In headache-free subjects, insomnia was associated with an increased risk of headache 11 years later. The association was particularly strong for chronic headache.

Parallel increases in strength and rate of force development (RFD) are well-known outcomes from the initial phase of resistance training. However, it is unknown whether neural adaptations with training contribute to improvements of both factors. The aim of this study was to examine whether changes in H-reflex amplitude with resistance training can explain the gain in strength or rather be associated with RFD. Twelve subjects carried out 3 weeks of isometric maximal plantarflexion training, whereas 12 subjects functioned as controls. H-reflexes were elicited in the soleus muscle during rest and sub-maximal contractions at 20 and 60% of maximal voluntary contraction (MVC). In addition, surface electromyography (sEMG) was recorded from the soleus, gastrocnemius and tibialis anterior muscles during MVC. The resistance training provided increases in maximal force of 18%, RFD of 28% and H-reflex amplitude during voluntary contractions of 17 and 15% while no changes occurred in the control group. In contrast, the maximal M-wave, the maximal H-reflex to maximal M-wave ratio during rest and sEMG during MVC did not change with training. There was a positive correlation between percentage changes in H-reflex amplitude and RFD with training (r = 0.59), while significant association between percentage changes in H-reflex amplitude and maximal force was not found. These findings indicate the occurrence of changed motoneuron excitability or presynaptic inhibition during the initial phase of resistance training. This is the first study to document that increased RFD with resistance training is associated with changes in reflex excitability.