A lack of sleep can lead to someone feeling grumpy or irritable. Inadequate sleep is also linked to depression and anxiety. Regularly engaging in physical activity improves sleep. A study examined sleep quality and physical activity. According to researchers, physical activity reduces sleep disturbance. Sex, gender, and age did not play a role in the benefits of exercise and sleep. Results showed exercise completed 3-8 hours before bed showed better improvement for sleep than any other time. Regular exercise improves quality of sleep and maintains insomnia.