Sleep and weight loss: the link that runs both ways

SASian Anderson, Writer and editor, MyGLP. Sources checked 21 October 2026.

What short sleep does to appetite

After a night of five hours, the hormone that signals hunger, ghrelin, goes up and the one that signals fullness, leptin, goes down. People eat a few hundred calories more the next day and choose more sugar and fat. The NHS sleep pages put the adult target at 7 to 9 hours. Most women in midlife, with work, children, hot flushes and a bladder that wakes them, get less.

On a weight loss medicine the hunger signal is damped, which softens the effect. The craving for sweet food after a bad night still shows up for many people, and so does the lack of energy to move.

Sleep apnoea: the one to ask about

Obstructive sleep apnoea is when the throat closes briefly over and over during sleep. You stop breathing for a few seconds, the brain jolts you half awake, and it repeats, sometimes hundreds of times a night. You wake exhausted with no idea why. It is common in people carrying extra weight, and it is under-diagnosed in women because the classic picture, a man who snores loudly, does not fit. In women it shows up as tiredness, headaches on waking, poor concentration, low mood and waking to pass urine. The NHS sleep apnoea page lists the signs and the test, which is a home sleep study.

Weight loss treats it. In the SURMOUNT-OSA trial, tirzepatide cut the number of breathing interruptions per hour by about half to two thirds over a year, and a share of participants no longer had apnoea at all. If you snore, wake unrefreshed, or a partner has noticed pauses in your breathing, ask the GP for a referral. Treating it, with a CPAP machine until the weight loss catches up, changes daytime life within weeks.

The medicine and your nights

• Nausea and reflux are worse lying flat. Eat the evening meal early and small, and do not lie down for an hour after it.
• If the weekly injection disturbs sleep, move it to the morning. The day and time are yours to choose as long as it is once a week.
• Some people report vivid dreams or broken sleep in the first weeks. It tends to settle. If it does not, tell the prescriber.
• A slow stomach plus a late large meal is the usual cause of 3am reflux. Raise the head of the bed by 10cm if it persists.

Hot flushes and night sweats

Perimenopause is the other big sleep thief for women over 40. Night sweats wake you, and the broken sleep raises appetite the next day. NICE guideline NG23 says HRT is the first-line treatment for flushes and sweats, and it can be taken alongside a weight loss medicine. Our perimenopause guide covers it.

The basics still apply

• Same wake time every day, including weekends. This matters more than bedtime.
• Daylight in the first hour after waking, even on a dull day. A ten-minute walk does it.
• No caffeine after 2pm. Caffeine has a half-life of about 5 hours.
• Alcohol helps you fall asleep and wrecks the second half of the night. See the alcohol guide.
• Cool, dark, quiet. 18 degrees is the usual target.
• Screens off 30 minutes before bed, or at least the brightness down and the doom-scroll replaced with something dull.
• If you cannot sleep after 20 minutes, get up and do something quiet in dim light. Lying awake trains the bed to mean wakefulness.

When to see a GP

Snoring with pauses, waking unrefreshed most days for a month, falling asleep in the day, or insomnia that has gone on for three months all deserve an appointment. The NHS offers a free online sleep course, Sleepio, in many areas, and cognitive behavioural therapy for insomnia works better than sleeping tablets in the long run.

Sources

1. Sleep and tiredness (NHS)
2. Sleep apnoea (NHS)
3. Tirzepatide for the treatment of obstructive sleep apnoea and obesity (SURMOUNT-OSA) (Malhotra et al, New England Journal of Medicine, 2024)
4. Menopause: identification and management (NG23) (NICE)
5. Insomnia (NHS)