“Ever since my husband retired six months ago, he’s been staying up all night and sleeping all day. Should I worry?”

It’s very common for people to get “off schedule” when they begin retirement, but this can have some significant effects on their quality of sleep and overall health. Restorative sleep can help ward off anxiety, depression, weakened immunity, weight gain and even diabetes and heart disease.

In general, the most restorative overnight sleep begins before midnight. During sleep, 90-minute cycles of light, deep and dreaming sleep repeat four to six times overnight. The amount of time you spend in each stage of sleep changes as the night progresses. You spend more time in the lighter stages as the night begins and more time in the deep, restorative stages before awakening in the morning. People who go to bed very late may not spend enough time in the deeper sleep stages.

The best thing your husband can do is go to bed and wake up at the same time every day. Since he no longer has to wake up to get to work, he could create a new morning routine, such as meeting friends at the gym or a local coffee shop.

If he has trouble sticking to a sleep schedule, he should consult a sleep specialist. Some adults and teens who are unable to fall asleep until the wee hours of the morning suffer from a sleep disorder known as delayed sleep phase syndrome. A sleep specialist can help the patient reset his/her circadian rhythm with treatments such as light therapy and the hormone melatonin.