よく寝る

You can use this phrase to describe yourself, your friends, or even your pets. It’s a simple subject-verb structure. You just say [Person] は よく寝る. If you want to talk about the past, you say よく寝た (I slept well). It’s incredibly flexible. You can use it as an adjective too. A よく寝る子 is a child who sleeps a lot. It’s one of those building-block phrases that makes you sound very natural.

Use this when you’re talking about health and daily routines. If someone asks how you feel after a long flight, say 昨日はよく寝ました. It’s great for bragging about your lazy Sunday. You can also use it when observing others. If your dog has been napping for six hours, よく寝るね is the perfect comment. It’s also a common way to compliment a baby’s growth. In Japan, sleeping babies are the ultimate symbol of peace.

Don't use this if you actually mean you 'overslept' by accident. For that, you need 寝坊した (nebō shita). よく寝る sounds intentional or like a positive habit. Also, don't use it for a quick power nap. That’s 昼寝 (hirune). If you fell asleep while watching a movie, use 寝落ちした (neochi shita). Using よく寝る there would make it sound like you planned a long slumber.

Japan has a complicated relationship with sleep. You might have heard of 居眠り (inemuri), which is napping in public or at work. It’s often seen as a sign of hard work. However, よく寝る is generally viewed positively in a domestic context. There is a famous Japanese proverb: 寝る子は育つ (neru ko wa sodatsu). it means 'Children who sleep well, grow well.' It reflects the belief that rest is the foundation of health and development.

You will often hear ぐっすり寝る (gussuri neru). This specifically means sleeping soundly or deeply. Another one is たっぷり寝る (tappuri neru). This emphasizes getting a 'full' or 'plenty' amount of sleep. If you want to be more formal, you might say よく睡眠をとる (yoku suimin o toru). But for daily life, よく寝る is the undisputed king of sleep phrases.