Struve was often described as a big and intimidating man. According to him, in his fifties, he was six feet tall, weighed 192 pounds, had gray hair and eyes. Struve was also known as persistent, dedicated and demanding, both to himself and others – the qualities preserved in his family for generations. He was first to arrive at the observatory, often working until late evening in the office, and then spending nights with a telescope. "He had only one interest and concern, namely, that astronomy should be developed and pushed to the maximum that was possible". As a result, Struve was usually overworked, developed an insomnia and often appeared as in a daze after a 2–3 hour sleep.