The Sleep Lengthening and Metabolic Health, Body Composition, Energy Balance and Cardiovascular Risk Study

Short sleep duration has been associated with increased risk of weight gain and development of non-communicable diseases. Sleep deprivation studies have suggested the link between restricted sleep and risk of adiposity and cardiometabolic dysregulation may be causal. However, the severity and acuteness of sleep restriction schedules in laboratory-based studies could hinder the ecological validity of the findings. The pragmatic way forward is to assess how improved sleep in habitually short sleepers impacts the aforementioned outcomes. This study assesses the feasibility of lengthening sleep in short sleepers, as well as how improved sleep duration and/or quality impact metabolic health, body composition, energy balance and cardiovascular risk.

Research Questions

* Is it feasible to improve sleep duration and quality in habitually short sleepers under free-living conditions?
* What are the effects of improved sleep duration and quality on body composition, energy balance, dietary intake, and cardio-metabolic risk factors?

Hypothesis

- Improved sleep duration and/or quality in habitually short sleepers will result in improved energy balance, diet quality, body composition, and cardio-metabolic risk profile.

Aims

* To assess the feasibility of improving sleep duration and/or quality in habitually short sleepers using behavioural approaches and public health messages targeting sleep hygiene.
* To identify how improved sleep duration and/or quality affect energy balance, diet quality, body composition, and cardio-metabolic risk profile.

Objectives

1. To develop a sleep extension strategy using behaviour change techniques (BCTs) targeting sleep hygiene.
2. To recruit healthy adults who are habitually short sleepers and randomise eligible participants to an intervention and control group.
3. To assess the feasibility and effectiveness of the intervention.
4. To measure energy balance, diet quality, body composition and cardio-metabolic risk factors pre- and post-treatment in the intervention and control groups.
5. To assess whether the intervention had an effect on the aforementioned parameters by comparing the intervention endpoints to control as well as baseline measures.
6. To run the statistical analysis both on an intention-to-treat basis as well as per-protocol.

Eligibility Criteria:
Inclusion Criteria:

* Healthy male and female adults (18-64 years)
* Habitually short sleepers (5-\<7 hours of sleep per night on average on weekdays) - this is self-reported at screening, and confirmed by actigraphy when baseline measurement is taken.
* BMI: 18.5 - \<30

Exclusion Criteria:

* Diagnosed medical conditions such as:
* Cardiovascular disease
* Type 1 or Type 2 Diabetes Mellitus
* Cancer (excluding basal carcinoma) in the past five years
* Chronic renal or liver disease
* Inflammatory bowel disease
* Hypo/hyperthyroidism
* Sleep conditions:
* Chronic use of sleeping aid medication
* Insomnia (Insomnia Severity Index - ISI Questionnaire)
* Sleep apnoea (Berlin Questionnaire)
* Extreme Chronotype (HorneOstberg questionnaire)
* Pregnancy or lactation
* Weight change of \>3 kg in the previous two months
* Previous or current high alcohol intake (\>28 units/week for males and \>21 units/week for females) or substance abuse
* Smoking
* Working hours outside 7 am - 7 pm
* Habitual napping (\>20 minutes per day on a regular basis)
* Obliged to wake and care for family/friends (e.g. new born child etc)
* Use of antidepressants
* Depressed mood (Center of Epidemiologic Studies of Depression 20-item scale questionnaire)
* Travel arrangements outside time zone within the periods of data collection
* Travel arrangements outside time zone within period of intervention/control condition
* Inability to adhere to a sleep hygiene intervention/sleep schedule due to time commitments