Neck pain (NP) is a prevalent symptom among migraine patients, but its disability on headache impact and the contributing factors for comorbid NP are poorly understood. This study aimed to investigate NP disability on the impact of headaches among migraineurs and factors linked to comorbid NP, including sleep-related variables. This cross-sectional study was conducted at a university hospital headache center, for headache patients at their first visits. Included in the study were 295 patients with migraines (217 females; 39.0  ±  10.8 years; 101 chronic migraine). Information on NP, history of physician-diagnosed cervical spine or disc disorders, detailed parameters of headache, and sleep and mood variables were collected. Logistic analysis of the severe impact of headache and contributing factors for NP were performed. NP was present in 153 participants (51.9%) with migraine, with high NP disability observed in 28 patients, and 125 patients had low NP disability. In multivariable analysis, NP disability, medication days per month, severe disability of migraine, and excessive daytime sleepiness were significant predictors for severe impact of headache. Thirty-seven patients with physician-diagnosed cervical spine or disc disorders were excluded from the NP analysis. Higher monthly headache days, female gender, and a high likelihood of obstructive sleep apnea were positively correlated with the presence of NP among migraineurs in multivariable analysis. Overall, the study highlights the potential impact of sleep-related variables and monthly headache days on NP in these patients. The high disability of NP was also associated with severe impact of headache.