People can suffer from varying degrees of insomnia for decades. Sometimes the insomnia can be worse than other times. People often talk about sleeping better when they go on vacation because they are away from the stresses and routine of daily life that has contributed to the insomnia.
It's very, very common for people with insomnia to take a sleep medication and it works for a few nights, weeks, months and then just quits.
If he says he has insomnia, he probably does. And it's a hard thing to understand if you've never had insomnia. Most people have no idea how horrible it is because they themselves have never gone days without any sleep or just a few hours here and there for months or years.