Introduction: The aim of this study was to assess the sleep quality and daytime sleepiness of resident doctors, to compare the sleep quality between surgical and medical branch residents and to examine effects of working hours, number of duties, clinical branches and some other daily habits on the sleep quality of resident doctors in a hospital in Turkey. Methods: A survey was conducted to gather data on (i) demographics, lifestyle and daily habits as well as to determine (ii) Epworth sleepiness scale (ESS) score and (iii) Pittsburgh sleep quality index (PSQI) scores of the participants. Data collection was based on the use of a self-administered questionnaire. Results: Of 138 resident doctors, 45.7% were classified as having good sleep quality based on a cut-off score of 5 in PSQI. The mean ESS and PSQI scores were 6.59 ±3.92 and 6.30 ±3.22, respectively. Significantly positive correlations were found between Epworth score and the number of night duties (p=0.010), working hours per week (p=0.006), total cigarettes per day (p=0.033), and daily tea consumption (p=0.013). Also, there were statistically significant positive correlations between PSQI scores and the number of night duties (p<0.001), working hours per week (p=0.007), total cigarettes per day (p=0.013) and daily coffee consumption (p=0.002). Surgical residents had significantly poor sleep quality (p=0.015). ESS score was higher in female residents and surgical residents, with a significant difference in these two sub-groups (p=0.018, p=0.008 respectively). Conclusions: Sleep quality and daytime sleepiness of the resident doctors were closely related to lifestyle factors including working hours, number of night duties and branch of residency as well as to certain demographic factors and daily habits. Giris: Bu calismanin amaci bir hastanede calisan asistanlarin uyku kalitesini ve gun ici uykululuk durumunu degerlendirmek, cerrahi ve medikal branslar arasinda uyku kalitesini karsilastirmak ve haftalik calisma saatleri, nobet sayilari , bazi gunluk aliskanliklar ve yasam tarzinin uyku kalitesi uzerine etkisini arastirmaktir. Yontem: Calisma uc bolumden olusan veriler ile yapilmistir; (i) demografik ozellikler, gunluk yasam tarzi ve aliskanliklarla ilgili bilgiler, (ii) Epworth uykululuk olcegi (ESS) skoru, (iii) Pittsburgh uyku kalitesi olcegi (PSQI) .Veriler katilimcilardan anket yoluyla ve etik kurallara uygun olarak alinmistir. Bulgular : 138 asistan doktorun % 45.7’sinin uyku kalitesi PSQI kesme puani olan 5’e gore uyku kalitesi iyi olarak degerlendirildi. Ortalama ESS ve PSIQ puanlari sirasiyla 6.59 ±3.92 ve 6.30 ±3.22 olarak bulundu. Epworth skoru ile gece nobet sayisi (p=0.010), haftalik calisma saatleri (p=0.006), gunluk icilen sigara sayisi (p=0.033), gunluk cay tuketimi (p=0.013) arasinda anlamli pozitif korelasyon bulundu. PSQI skorlari ile, gece nobeti sayilari (p<0.001), haftalik calisma saatleri (p=0.007), gunde icilen sigara sayisi (p=0.013), gunluk kahve tuketimi (p=0.002) arasinda anlamli pozitif korelasyon saptandi. Cerrahi bolum asistanlarinin uyku kalitesi daha dusuk rapor edildi (p=0.015). ESS skorlari kadin asistanlarda ve cerrahi bolum asistanlarinda daha yuksek gozlendi ve bu farklar istatistiksel olarak anlamli bulundu (sirasiyla p=0.018, p=0.008). Sonuc: Asistan doktorlarin uyku kalitesi ve gun ici uykululuk durumu, demografik faktorler ve gunluk aliskanliklarla ilgili oldugu kadar, haftalik calisma saatlerinin uzunlugu, nobet sayilari ve asistanlik yapilan bolum gibi yasam tarzi faktorleriyle de yakindan iliskilidir.