4. Pregnancy

Many women also report feeling extremely fatigued during pregnancy, especially during the first and third trimesters. Considering the physical and emotional demands of pregnancy and the prevalence of sleep disorders among pregnant women, it’s no wonder that expectant mothers become so tired. One of the reasons for fatigue and sleep problems during pregnancy are changing hormone levels. For example, rising progesterone levels may partly explain excessive daytime sleepiness, especially in the first trimester.